ci: udpate checkout version

[hkershaw-brown]

Description:

Please provide a summary of the change and include any relevant motivation and context.

This pull requests updates github actions to node.js 24 version ahead of June 2nd soft deadline (and Sept 16th 2026 hard deadline).
For an example of the warning from GitHub see annotation on https://github.com/NCAR/DART/actions/runs/26170351198

Fixes issue

fixes #1099

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• CI change

Documentation changes needed?

• My change requires a change to the documentation.
  • I have updated the documentation accordingly.

Tests

Please describe any tests you ran to verify your changes.
This pull request is the test to see if the actions run correctly on GitHub and the CIRRUS runners

Checklist for merging

• Updated changelog entry
• Documentation updated
• Update conf.py

Checklist for release

• Merge into main
• Create release from the main branch with appropriate tag
• Delete feature-branch

Testing Datasets

• Dataset needed for testing available upon request
• Dataset download instructions included
• No dataset needed

[mjs2369]

Everything looks good