Upgrade GitHub Actions for Node 24 compatibility

[salmanmkc]

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	v4	v5	Release	build_kernel_windows.yaml, rust.yaml
actions/checkout	v4, v5	v6	Release	build_kernel.yaml, build_kernel_macos.yaml, build_kernel_rocm.yaml, build_kernel_windows.yaml, build_kernel_xpu.yaml, check_variants.yaml, docker-build-push.yaml, kernel_abi_python_release.yaml, nix_fmt.yaml, rust.yaml, test_extra_commands.yaml, test_python.yaml
actions/download-artifact	v4	v7	Release	build_kernel.yaml, kernel_abi_python_release.yaml
actions/setup-python	v5	v6	Release	kernel_abi_python_release.yaml
actions/upload-artifact	v4	v6	Release	build_kernel.yaml, kernel_abi_python_release.yaml

Context

Per GitHub's announcement, 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.