Upgrade GitHub Actions for Node 24 compatibility (#25572)

## Summary

Upgrade GitHub Actions to their latest versions to ensure compatibility with Node 24, as Node 20 will reach end-of-life in April 2026.

## Changes

| Action | Old Version(s) | New Version | Release | Files |
|--------|---------------|-------------|---------|-------|
| `actions/cache` | [`1bd1e32`](https://github.com/actions/cache/commit/1bd1e32a3bdc45362d1e726936510720a7c30a57) | [`8b402f5`](https://github.com/actions/cache/commit/8b402f58fbc84540c8b491a91e594a4576fec3d7) | [Release](https://github.com/actions/cache/releases/tag/v5) | clear_caches.yml |
| `actions/checkout` | [`8ade135`](https://github.com/actions/checkout/commit/8ade135a41bc03ea155e62e844d188df1ea18608) | [`8e8c483`](https://github.com/actions/checkout/commit/8e8c483db84b4bee98b60c0593521ed34d9990e8) | [Release](https://github.com/actions/checkout/releases/tag/v6) | scorecard.yml, staleness_refresh.yml, update_php_repo.yml |
| `actions/download-artifact` | [`018cc2c`](https://github.com/actions/download-artifact/commit/018cc2cf5baa6db3ef3c5f8a56943fffe632ef53), [`fa0a91b`](https://github.com/actions/download-artifact/commit/fa0a91b85d4f404e444e00e005971372dc801d16) | [`37930b1`](https://github.com/actions/download-artifact/commit/37930b1c2abaa49bbe596cd826c3c89aef350131) | [Release](https://github.com/actions/download-artifact/releases/tag/v7) | test_cpp.yml, test_php_ext.yml, test_upb.yml |
| `actions/setup-dotnet` | [`3447fd6`](https://github.com/actions/setup-dotnet/commit/3447fd6a9f9e57506b15f895c5b76d3b197dc7c2) | [`baa11fb`](https://github.com/actions/setup-dotnet/commit/baa11fbfe1d6520db94683bd5c7a3818018e4309) | [Release](https://github.com/actions/setup-dotnet/releases/tag/v5) | test_csharp.yml |
| `actions/setup-java` | [`3a4f6e1`](https://github.com/actions/setup-java/commit/3a4f6e1af504cf6a31855fa899c6aa5355ba6c12) | [`be666c2`](https://github.com/actions/setup-java/commit/be666c2fcd27ec809703dec50e508c2fdc7f6654) | [Release](https://github.com/actions/setup-java/releases/tag/v5) | test_bazel.yml |
| `actions/setup-python` | [`39cd149`](https://github.com/actions/setup-python/commit/39cd14951b08e74b54015e9e001cdefcf80e669f), [`e797f83`](https://github.com/actions/setup-python/commit/e797f83bcb11b83ae66e0230d6156d7c80228e7c) | [`a309ff8`](https://github.com/actions/setup-python/commit/a309ff8b426b58ec0e2a45f0f869d46889d02405) | [Release](https://github.com/actions/setup-python/releases/tag/v6) | test_python.yml, test_upb.yml |
| `actions/stale` | [`b69b346`](https://github.com/actions/stale/commit/b69b346013879cedbf50c69f572cd85439a41936) | [`9971854`](https://github.com/actions/stale/commit/997185467fa4f803885201cee163a9f38240193d) | [Release](https://github.com/actions/stale/releases/tag/v10) | janitor.yml |
| `actions/upload-artifact` | [`5076954`](https://github.com/actions/upload-artifact/commit/50769540e7f4bd5e21e526ee35c689e35e0d6874), [`v4`](https://github.com/actions/upload-artifact/releases/tag/v4) | [`b7c566a`](https://github.com/actions/upload-artifact/commit/b7c566a772e6b6bfb58ed0dc250532a479d7789f) | [Release](https://github.com/actions/upload-artifact/releases/tag/v6) | scorecard.yml, test_cpp.yml, test_php_ext.yml, test_ruby.yml, test_upb.yml |

## Context

Per [GitHub's announcement](https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/), Node 20 is being deprecated and runners will begin using Node 24 by default starting March 4th, 2026.

### Why this matters

- **Node 20 EOL**: April 2026
- **Node 24 default**: March 4th, 2026
- **Action**: Update to latest action versions that support Node 24

### Security Note

Actions that were previously pinned to commit SHAs remain pinned to SHAs (updated to the latest release SHA) to maintain the security benefits of immutable references.

### Testing

These changes only affect CI/CD workflow configurations and should not impact application functionality. The workflows should be tested by running them on a branch before merging.

Closes #25572

COPYBARA_INTEGRATE_REVIEW=https://github.com/protocolbuffers/protobuf/pull/25572 from salmanmkc:upgrade-github-actions-node24 ef77dcfa4f79196b9a222d3d24f773d7a6b3966e
PiperOrigin-RevId: 874140973