Sync to EF Core preview.6

[roji]

This syncs the provider to the latest EF Core preview.6 build so EFCore.PG can continue tracking the current EF 11 preview train.

Changes

• Bump the provider version and EF/Microsoft.Extensions dependencies to preview.6.
• Pin the .NET 11 preview.6 SDK/runtime and enable Microsoft.Testing.Platform for test execution.
• Migrate test infrastructure to xUnit v3, including async lifetime updates and provider-specific skip traits.
• Update provider tests and SQL baselines for preview.6 query pipeline changes.
• Fix preview.6 compatibility issues around JSON update SQL generation, connection creation interception, TPC generated-key seeding, value converter timestamp mappings, and provider-specific FromSql behavior.

Validation

• dotnet build EFCore.PG.slnx --no-restore -v:minimal -m:1
• dotnet exec test/EFCore.PG.Tests/bin/Debug/net11.0/Npgsql.EntityFrameworkCore.PostgreSQL.Tests.dll --filter-not-trait category=failing --no-progress --timeout 5m
• dotnet exec test/EFCore.PG.FunctionalTests/bin/Debug/net11.0/Npgsql.EntityFrameworkCore.PostgreSQL.FunctionalTests.dll --filter-not-trait category=failing --max-threads 4 --timeout 30m --long-running 120 --no-progress

[Copilot]

Pull request overview

This PR syncs EFCore.PG to EF Core 11 preview.6, updating provider and test infrastructure to stay aligned with the EF 11 preview train and its query/update pipeline changes.

Changes:

• Bumps EF Core / Microsoft.Extensions package versions to 11.0.0-preview.6.*, updates provider version prefix, and pins the .NET 11 preview.6 SDK via global.json.
• Migrates tests to xUnit v3 + Microsoft.Testing.Platform runner and updates various fixtures/lifetimes accordingly.
• Updates multiple functional tests and SQL baselines to match preview.6 behaviors (query SQL shape, bulk update SQL, JSON update SQL generation, etc.).

Show a summary per file

File	Description
test/EFCore.PG.FunctionalTests/ValueConvertersEndToEndNpgsqlTest.cs	Updates DateTime conversion expectations and explicitly configures timestamp column types.
test/EFCore.PG.FunctionalTests/Update/JsonUpdateNpgsqlTest.cs	Removes redundant conditional attributes on JSON update tests.
test/EFCore.PG.FunctionalTests/TestUtilities/RequiresPostgisAttribute.cs	Converts PostGIS requirement into a trait-based “failing” categorization for filtering under xUnit v3.
test/EFCore.PG.FunctionalTests/TestUtilities/MinimumPostgresVersionAttribute.cs	Converts minimum PostgreSQL version requirement into a trait-based “failing” categorization for filtering under xUnit v3.
test/EFCore.PG.FunctionalTests/SequenceEndToEndTest.cs	Updates async lifetime methods to return ValueTask (xUnit v3 pattern).
test/EFCore.PG.FunctionalTests/Scaffolding/NpgsqlDatabaseModelFactoryTest.cs	Updates fixture async initialization signature to ValueTask.
test/EFCore.PG.FunctionalTests/Query/UdfDbFunctionNpgsqlTests.cs	Removes a conditional skip for a RELEASE-only test override.
test/EFCore.PG.FunctionalTests/Query/Translations/MathTranslationsNpgsqlTest.cs	Updates SQL assertions to include additional SQL statements for Sign translations.
test/EFCore.PG.FunctionalTests/Query/Translations/ByteArrayTranslationsNpgsqlTest.cs	Removes redundant conditional attribute from an override.
test/EFCore.PG.FunctionalTests/Query/SqlQueryNpgsqlTest.cs	Unskips several tests and updates SQL baselines/parameter naming for preview.6 behavior.
test/EFCore.PG.FunctionalTests/Query/PrimitiveCollectionsQueryNpgsqlTest.cs	Removes redundant conditional attribute from an override.
test/EFCore.PG.FunctionalTests/Query/NorthwindGroupByQueryNpgsqlTest.cs	Updates SQL baseline (alias changes) and removes a skip.
test/EFCore.PG.FunctionalTests/Query/NorthwindDbFunctionsQueryNpgsqlTest.cs	Updates platform skip attribute usage for preview.6/xUnit v3.
test/EFCore.PG.FunctionalTests/Query/LegacyTimestampQueryTest.cs	Updates async disposal to ValueTask and simplifies completion.
test/EFCore.PG.FunctionalTests/Query/Inheritance/TPCInheritanceQueryNpgsqlTest.cs	Removes a provider-specific override that expected a key conflict, aligning with updated seeding.
test/EFCore.PG.FunctionalTests/Query/Inheritance/TPCInheritanceQueryNpgsqlFixture.cs	Adds seeding logic to advance the TPC sequence after manual inserts.
test/EFCore.PG.FunctionalTests/Query/FromSqlQueryNpgsqlTest.cs	Reworks invalid-cast tests to use provider-specific SQL and assertions.
test/EFCore.PG.FunctionalTests/Query/EntitySplittingQueryNpgsqlTest.cs	Re-enables previously skipped tests and adds explicit SQL baselines.
test/EFCore.PG.FunctionalTests/Query/ComplexNavigationsSharedTypeQueryNpgsqlTest.cs	Removes skips for previously failing query scenarios.
test/EFCore.PG.FunctionalTests/Query/CompatibilityQueryNpgsqlTest.cs	Updates async lifetime methods to ValueTask.
test/EFCore.PG.FunctionalTests/Query/Associations/OwnedNavigations/OwnedNavigationsCollectionNpgsqlTest.cs	Removes redundant conditional attribute from an override.
test/EFCore.PG.FunctionalTests/Query/Associations/OwnedJson/OwnedJsonCollectionNpgsqlTest.cs	Removes redundant conditional attribute from an override.
test/EFCore.PG.FunctionalTests/Query/Associations/Navigations/NavigationsCollectionNpgsqlTest.cs	Removes redundant conditional attribute from an override.
test/EFCore.PG.FunctionalTests/Query/Associations/ComplexJson/ComplexJsonCollectionNpgsqlTest.cs	Removes redundant conditional attribute from an override.
test/EFCore.PG.FunctionalTests/Query/AdHocMiscellaneousQueryNpgsqlTest.cs	Re-enables a UDF store-type test and adds a provider-specific DbContext/model setup.
test/EFCore.PG.FunctionalTests/Migrations/MigrationsNpgsqlTest.cs	Removes skips for converter-related primitive collection migration tests.
test/EFCore.PG.FunctionalTests/Migrations/MigrationsInfrastructureNpgsqlTest.cs	Removes temporary skips on migration apply/revert tests.
test/EFCore.PG.FunctionalTests/LazyLoadProxyNpgsqlTest.cs	Removes conditional attributes around tests that were previously annotated as MARS-related.
test/EFCore.PG.FunctionalTests/JsonTypesNpgsqlTest.cs	Removes redundant conditional attributes from JSON tests.
test/EFCore.PG.FunctionalTests/CustomConvertersNpgsqlTest.cs	Removes a skip around DateTimeOffset-related test override.
test/EFCore.PG.FunctionalTests/ConvertToProviderTypesNpgsqlTest.cs	Removes a skip around DateTimeOffset-related test override.
test/EFCore.PG.FunctionalTests/ConnectionInterceptionNpgsqlTest.cs	Re-enables and reimplements connection creation interception tests; adjusts provider configuration.
test/EFCore.PG.FunctionalTests/ComputedColumnTest.cs	Updates async lifetime methods to ValueTask.
test/EFCore.PG.FunctionalTests/BulkUpdates/NorthwindBulkUpdatesNpgsqlTest.cs	Updates bulk update SQL baselines and adjusts assertions for nullable navigation results.
test/EFCore.PG.FunctionalTests/BuiltInDataTypesNpgsqlTest.cs	Removes a skip around DateTimeOffset-related test override.
test/Directory.Build.props	Switches tests to Microsoft.Testing.Platform runner and updates xUnit package references/usings/analyzer suppressions.
src/EFCore.PG/Update/Internal/NpgsqlUpdateSqlGenerator.cs	Minor refactor around JSON path indices extraction with added debug assertion.
global.json	Pins .NET 11 preview.6 SDK and configures Microsoft.Testing.Platform as the test runner.
Directory.Packages.props	Bumps EF/Microsoft.Extensions versions to preview.6 and updates xUnit package versions to v3 prereleases.
Directory.Build.props	Bumps VersionPrefix to 11.0.0-preview.6.

Copilot's findings

• Files reviewed: 41/42 changed files
• Comments generated: 2

[Copilot]

Copilot's findings

• Files reviewed: 42/43 changed files
• Comments generated: 3

[Copilot]

Copilot's findings

• Files reviewed: 42/43 changed files
• Comments generated: 3

[Copilot]

Copilot's findings

• Files reviewed: 42/43 changed files
• Comments generated: 5

[Copilot]

Copilot's findings

• Files reviewed: 42/43 changed files
• Comments generated: 2