Migrate to ESM and upgrade dependencies

[priyagupta108]

Description:
Convert to ESM, update imports/tests/configs for ESM, and bump dependencies.

Related issue:
Add link to the related issue.

Check list:

• Mark if documentation changes are required.
• Mark if tests were added or updated to cover the changes.

[Copilot]

Pull request overview

This PR migrates the action’s TypeScript/Node codebase to ESM (NodeNext), updates runtime path handling and intra-repo imports for ESM compatibility, modernizes Jest/ESLint/Prettier configuration for ESM, and upgrades runtime/dev dependencies (notably the @actions/* toolkits).

Changes:

• Switch TypeScript compilation to ESM via NodeNext, update relative imports to include .js, and replace __dirname usage with import.meta.url path resolution.
• Update testing and linting for ESM: add jest.config.ts, add flat-config eslint.config.mjs, and introduce tsconfig.eslint.json.
• Bump dependencies and refresh licensed dependency metadata.

Reviewed changes

Copilot reviewed 48 out of 59 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
tsconfig.json	Switch TS output/module resolution to NodeNext/ES2022 and adjust excludes for ESM-era config layout.
tsconfig.eslint.json	Add dedicated TS config to support ESLint/type-aware linting across src/tests (and root TS).
src/system.ts	Update local type import to .js extension for ESM compatibility.
src/setup-go.ts	Update entrypoint import to .js extension for ESM compatibility.
src/main.ts	Update local imports to .js and replace __dirname matcher path logic with import.meta.url-based resolution.
src/installer.ts	Update local imports to .js, refactor Go version fetching to use new helper module, and add Error.cause for download errors.
src/go-version-fetch.ts	New helper module extracting Go “versions dist” fetch logic for cleaner ESM/module boundaries.
src/cache-utils.ts	Update local import to .js and reformat multi-import for ESM.
src/cache-save.ts	Update local imports to .js for ESM.
src/cache-restore.ts	Update local imports to .js for ESM.
package.json	Mark package as ESM (type: module), modernize tool scripts, and bump dependencies/devDependencies.
jest.config.ts	Add ESM-aware Jest config using ts-jest with ESM settings and moduleNameMapper for .js specifiers.
jest.config.js	Remove legacy CJS Jest config.
eslint.config.mjs	Add ESLint flat config (ESM) aligned with new toolchain.
dist/setup/package.json	Mark the bundled setup distribution folder as ESM (type: module).
dist/cache-save/package.json	Mark the bundled cache-save distribution folder as ESM (type: module).
.prettierrc.json	Add JSON-based Prettier config suitable for ESM repos.
.prettierrc.js	Remove legacy CJS Prettier config.
.licensed.yml	Allow additional licenses introduced by dependency upgrades and update reviewed list.
.eslintrc.js	Remove legacy ESLint RC config (superseded by flat config).
.eslintignore	Remove legacy ESLint ignore file (superseded by flat config ignores).
tests/windows-toolcache.test.ts	Convert Jest tests to ESM-friendly mocking (unstable_mockModule) and explicit jest globals import.
tests/utils.test.ts	Update src import to .js and adopt explicit jest globals import.
tests/setup-go.test.ts	Convert mocks/imports to ESM approach, update JSON imports to import attributes, and adjust spies to mock-based types.
tests/cache-utils.test.ts	Convert to ESM-friendly mocking and adjust spies to mock-based types.
tests/cache-save.test.ts	Convert to ESM-friendly mocking (including fs), and update imports to .js.
tests/cache-restore.test.ts	Convert to ESM-friendly mocking and update imports to .js.
.licenses/npm/strnum.dep.yml	Update licensed metadata version for dependency changes.
.licenses/npm/semver.dep.yml	Add new licensed metadata for upgraded semver.
.licenses/npm/semver-6.3.1.dep.yml	Remove old semver licensed metadata entry.
.licenses/npm/path-expression-matcher.dep.yml	Update licensed metadata version for dependency changes.
.licenses/npm/minimatch-3.1.5.dep.yml	Add licensed metadata for minimatch v3 line (transitive).
.licenses/npm/minimatch-10.2.5.dep.yml	Add licensed metadata for minimatch v10 line (transitive).
.licenses/npm/is-unsafe.dep.yml	Update licensed metadata content to match the correct package/version.
.licenses/npm/fast-xml-parser.dep.yml	Update licensed metadata version for dependency changes.
.licenses/npm/brace-expansion-5.0.6.dep.yml	Add licensed metadata for newer brace-expansion (transitive).
.licenses/npm/brace-expansion-1.1.15.dep.yml	Update licensed metadata version for dependency changes.
.licenses/npm/balanced-match-4.0.4.dep.yml	Add licensed metadata for newer balanced-match (transitive).
.licenses/npm/balanced-match-1.0.2.dep.yml	Add licensed metadata for balanced-match (transitive).
.licenses/npm/anynum.dep.yml	Update licensed metadata version for dependency changes.
.licenses/npm/@typespec/ts-http-runtime.dep.yml	Update licensed metadata version/homepage for dependency changes.
.licenses/npm/@azure/storage-common.dep.yml	Update licensed metadata version/homepage for dependency changes.
.licenses/npm/@azure/storage-blob.dep.yml	Update licensed metadata version/homepage for dependency changes.
.licenses/npm/@azure/core-xml.dep.yml	Update licensed metadata version for dependency changes.
.licenses/npm/@azure/core-rest-pipeline.dep.yml	Update licensed metadata version/homepage for dependency changes.
.licenses/npm/@azure/core-http-compat.dep.yml	Update licensed metadata version for dependency changes.
.licenses/npm/@azure/core-client.dep.yml	Update licensed metadata version for dependency changes.
.licenses/npm/@azure/abort-controller.dep.yml	Add licensed metadata for abort-controller (transitive).
.licenses/npm/@actions/tool-cache.dep.yml	Update licensed metadata version for toolkit upgrade.
.licenses/npm/@actions/io.dep.yml	Update licensed metadata version for toolkit upgrade.
.licenses/npm/@actions/http-client.dep.yml	Update licensed metadata version for toolkit upgrade.
.licenses/npm/@actions/glob-0.7.0.dep.yml	Add licensed metadata for newer @actions/glob (toolkit upgrade).
.licenses/npm/@actions/glob-0.6.1.dep.yml	Update licensed metadata version for toolkit upgrade path.
.licenses/npm/@actions/exec.dep.yml	Update licensed metadata version for toolkit upgrade.
.licenses/npm/@actions/core.dep.yml	Update licensed metadata version for toolkit upgrade.
.licenses/npm/@actions/cache.dep.yml	Update licensed metadata version for toolkit upgrade.

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