test(state): mark the deprecated serializer-aware provider test

[soyuka]

Fixes the PHPUnit (PHP 8.5) (no deprecations) job, which runs vendor/bin/phpunit --fail-on-deprecation --display-deprecations and currently reports:

1 test triggered 1 deprecation:

1) src/State/SerializerAwareProviderTrait.php:33
Since api-platform/core 4.2: The "ApiPlatform\State\SerializerAwareProviderInterface" interface is
deprecated and will be removed in 5.0. It violates the dependency injection principle.

Triggered by:

* ApiPlatform\Tests\Functional\JsonLd\SerializableItemDataProviderTest::testGetSerializableResource

Why

The SerializableProvider test fixture implements SerializerAwareProviderInterface. DataProviderPass therefore adds a setSerializerLocator() method call to its definition, and the trait triggers the 4.2 deprecation when the service is instantiated during the request.

The deprecation is correct and intentional — the interface still ships in 4.3 and is only removed in 5.0, so the code path must stay covered. Only the test needs to declare that it exercises a deprecated feature.

Change

#[IgnoreDeprecations] plus expectUserDeprecationMessage() on the test, following the convention already used in tests/Functional/EnumDenormalizationValidationTest.php. Using the expectation rather than a bare ignore keeps the deprecation asserted, so it will be noticed when the interface is dropped in 5.0.

Verified locally

Run	Before	After
--fail-on-deprecation --display-deprecations with ignoreIndirectDeprecations="false"	reproduces the CI message verbatim	OK (1 test, 3 assertions)
same, with the committed config	silent	OK (1 test, 3 assertions)

The expectation is satisfied under both settings, so it does not depend on how the deprecation is categorised.

Note: this is the only remaining red check on #8425.