github action to run pytest for pushes to pytools directory

[hkershaw-brown]

Description:

Add a GitHub Actions workflow (pytools-tests.yml) which runs pytest on the pytools directory.
Only runs when when changes are made inside the pytools directory, any branch.
Does not run for changes elsewhere.

Gone with python versions 3.10 (<3.10 is end-of-life) to 3.14 (latest stable).

Fixes issue

fixes #1042

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

Documentation changes needed?

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

Tests

Committed changes to pytools directory to run the action.
https://github.com/NCAR/DART/actions/runs/21884963160/job/63177362755
Committed changes to files outside pytools confirmed action does not run.

Note force pushed to this branch to remove these two test commits.

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]

@hkershaw-brown nice addition to the actions! Everything looks good, including the test runs of the action