Remove units from guidewindow

[WilliamJamieson]

This PR updates roman_datamodels to support spacetelescope/rad#499.

Tasks

• [ ] Update or add relevant roman_datamodels tests.
• [ ] Update relevant docstrings and / or docs/ page.
• [ ] 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>").

News fragment change types:

- ``changes/.feature.rst``: new feature - ``changes/.bugfix.rst``: fixes an issue - ``changes/.doc.rst``: documentation change - ``changes/.removal.rst``: deprecation or removal of public API - ``changes/.misc.rst``: infrastructure or miscellaneous change

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 97.41%. Comparing base (087a60d) to head (0d54c71). Report is 65 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #415 +/- ## ========================================== - Coverage 97.56% 97.41% -0.15% ========================================== Files 30 37 +7 Lines 2788 3449 +661 ========================================== + Hits 2720 3360 +640 - Misses 68 89 +21 ```

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