Fix romancal CI test

[WilliamJamieson]

Currently we are seeing the romancal tests failing, see https://github.com/spacetelescope/rad/actions/runs/19817201686. The failure appears to be due galsim not having a wheel available for Python 3.14, which is the python version those tests are currently being run on. The galsim dependency for romancal comes from romanisim which was added as a romancal dependency by spacetelescope/romancal#2036.

This PR simply runs the romancal tests on Python 3.13 instead of the latest Python, Python 3.14.

Tasks

• Update or add relevant rad tests.
• Update relevant docstrings and / or docs/ page.
• Does this PR change any schema files?
  • Schema changes were discussed at RAD Review Board meeting.
• Does this PR change any API used downstream? (If not, label with no-changelog-entry-needed.)
  • Write news fragment(s) in changes/: echo "changed something" > changes/<PR#>.<changetype>.rst (see below for change types).
  • Start a romancal regression test (https://github.com/spacetelescope/RegressionTests/actions/workflows/romancal.yml) with this branch installed ("git+https://github.com/<fork>/rad@<branch>").
  • Update relevant roman_datamodels utilities and tests.

News fragment change types:

• changes/<PR#>.feature.rst: new feature
• changes/<PR#>.bugfix.rst: fixes an issue
• changes/<PR#>.doc.rst: documentation change
• changes/<PR#>.removal.rst: deprecation or removal of public API
• changes/<PR#>.misc.rst: infrastructure or miscellaneous change

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.87%. Comparing base (ce9f6df) to head (804f665).
⚠️ Report is 72 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #774   +/-   ##
=======================================
  Coverage   85.87%   85.87%           
=======================================
  Files          14       14           
  Lines        1069     1069           
=======================================
  Hits          918      918           
  Misses        151      151           

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[WilliamJamieson]

I'm honestly surprised this wasn't an issue earlier, as romancal does not support Python 3.14: https://github.com/spacetelescope/romancal/blob/c9d9845038e39cd841e73fea90e21f0f8e90f8dd/pyproject.toml#L5. It seems to have "run just fine" on 3.14 back before the romanisim change in romancal see: https://github.com/spacetelescope/rad/actions/runs/19226355235/job/54954407998#step:10:137. This run appears to have happened after spacetelescope/romancal#2030 which added a romancal upper python <3.14 pin.