Migrate to ESM and upgrade dependencies

[priyagupta108]

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• Mark if documentation changes are required.
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[Copilot]

Pull request overview

This PR migrates the setup-python GitHub Action codebase to ESM (TypeScript NodeNext + package "type": "module") while upgrading core runtime/tooling dependencies, and updating Jest/ESLint/Prettier configuration to align with the new module system.

Changes:

• Switch TypeScript compilation to module: NodeNext and update internal imports to explicit .js specifiers for ESM compatibility.
• Upgrade @actions/*, Jest, ESLint, TypeScript, and related tooling; migrate ESLint to flat config and Jest to an ESM-compatible TS config.
• Update tests to ESM patterns (top-level await, jest.unstable_mockModule) and refresh dependency license metadata.

Reviewed changes

Copilot reviewed 55 out of 66 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
tsconfig.json	Switch TS output module kind to NodeNext and exclude ESM Jest config from build compilation.
tsconfig.eslint.json	Add a dedicated TS config for ESLint/IDE usage with broader includes.
src/utils.ts	Add explicit string[] typings to avoid implicit any[] under strict mode.
src/setup-python.ts	Update relative imports to .js, add ESM-compatible __dirname replacement, and adjust a catch clause.
src/install-python.ts	Update utils import to .js and modernize ExecOptions type import.
src/install-pypy.ts	Update utils import to .js for ESM.
src/install-graalpy.ts	Update utils import to .js for ESM.
src/find-python.ts	Update local imports to .js for ESM.
src/find-pypy.ts	Update local imports to .js for ESM.
src/find-graalpy.ts	Update local imports to .js for ESM.
src/cache-save.ts	Update cache-distributor import to .js for ESM.
src/cache-distributions/poetry-cache.ts	Update relative imports to .js for ESM.
src/cache-distributions/pipenv-cache.ts	Update relative imports to .js for ESM.
src/cache-distributions/pip-cache.ts	Update relative imports to .js for ESM.
src/cache-distributions/cache-factory.ts	Update relative imports to .js for ESM.
src/cache-distributions/cache-distributor.ts	Update relative imports to .js for ESM.
package.json	Declare ESM package type, update scripts for flat ESLint/Jest ESM, and upgrade dependencies/devDependencies.
jest.config.ts	Add Jest TS config for ESM + ts-jest (useESM) and .js-specifier mapping.
jest.config.js	Remove legacy CommonJS Jest config.
eslint.config.mjs	Add ESLint flat config (TS + Jest + Node rules + Prettier).
dist/setup/package.json	Mark the bundled action entrypoint directory as ESM.
dist/cache-save/package.json	Mark the bundled post-action entrypoint directory as ESM.
.prettierrc.json	Add JSON-based Prettier config (replacing JS config).
.prettierrc.js	Remove legacy JS-based Prettier config.
.licensed.yml	Add newly-introduced transitive deps to the reviewed allowlist.
.eslintrc.js	Remove legacy ESLint config (replaced by flat config).
.eslintignore	Remove legacy ignore file (handled by flat config ignores).
tests/utils.test.ts	Convert tests to ESM-style module mocking and dynamic imports.
tests/install-python.test.ts	Convert tests to ESM-style module mocking and dynamic imports.
tests/install-pypy.test.ts	Convert tests to ESM-style module mocking/dynamic imports and JSON import assertions.
tests/install-graalpy.test.ts	Convert tests to ESM-style module mocking/dynamic imports and JSON import assertions.
tests/finder.test.ts	Convert tests to ESM-style module mocking/dynamic imports and adjust mocking strategy.
tests/find-python.test.ts	Update imports to .js for ESM.
tests/find-pypy.test.ts	Convert tests to ESM-style module mocking/dynamic imports and JSON import assertions.
tests/find-graalpy.test.ts	Convert tests to ESM-style module mocking/dynamic imports and JSON import assertions.
tests/cache-save.test.ts	Convert tests to ESM-style module mocking/dynamic imports.
tests/cache-restore.test.ts	Convert tests to ESM-style module mocking/dynamic imports and async restore result handling.
.licenses/npm/semver.dep.yml	Update semver license metadata to v7.8.5.
.licenses/npm/semver-6.3.1.dep.yml	Remove old semver v6.3.1 license metadata.
.licenses/npm/path-expression-matcher.dep.yml	Update path-expression-matcher license metadata version.
.licenses/npm/minimatch-3.1.5.dep.yml	Add minimatch v3.1.5 license metadata.
.licenses/npm/minimatch-10.2.5.dep.yml	Add minimatch v10.2.5 license metadata.
.licenses/npm/fast-xml-parser.dep.yml	Update fast-xml-parser license metadata version/homepage formatting.
.licenses/npm/brace-expansion-5.0.6.dep.yml	Update/add brace-expansion v5.0.6 license metadata content.
.licenses/npm/brace-expansion-1.1.15.dep.yml	Update brace-expansion v1.1.x license metadata version.
.licenses/npm/balanced-match-4.0.4.dep.yml	Add balanced-match v4.0.4 license metadata.
.licenses/npm/balanced-match-1.0.2.dep.yml	Add balanced-match v1.0.2 license metadata.
.licenses/npm/@typespec/ts-http-runtime.dep.yml	Update @typespec/ts-http-runtime license metadata version/homepage.
.licenses/npm/@azure/storage-common.dep.yml	Update @azure/storage-common license metadata version/homepage.
.licenses/npm/@azure/storage-blob.dep.yml	Update @azure/storage-blob license metadata version/homepage.
.licenses/npm/@azure/core-xml.dep.yml	Update @azure/core-xml license metadata version.
.licenses/npm/@azure/core-rest-pipeline.dep.yml	Update @azure/core-rest-pipeline license metadata version/homepage.
.licenses/npm/@azure/core-http-compat.dep.yml	Update @azure/core-http-compat license metadata version.
.licenses/npm/@azure/core-client.dep.yml	Update @azure/core-client license metadata version.
.licenses/npm/@azure/abort-controller.dep.yml	Add @azure/abort-controller v2.x license metadata.
.licenses/npm/@actions/tool-cache.dep.yml	Update @actions/tool-cache license metadata version.
.licenses/npm/@actions/io.dep.yml	Update @actions/io license metadata version.
.licenses/npm/@actions/http-client.dep.yml	Update @actions/http-client license metadata version.
.licenses/npm/@actions/glob-0.7.0.dep.yml	Add @actions/glob v0.7.0 license metadata.
.licenses/npm/@actions/glob-0.6.1.dep.yml	Update @actions/glob v0.6.x license metadata version reference.
.licenses/npm/@actions/exec.dep.yml	Update @actions/exec license metadata version.
.licenses/npm/@actions/core.dep.yml	Update @actions/core license metadata version.
.licenses/npm/@actions/cache.dep.yml	Update @actions/cache license metadata version.

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