drop python 3.9

[braingram]

Drops support for python 3.9 inline with https://github.com/spacetelescope/jwst/pull/8365

Checklist

• [ ] added entry in CHANGES.rst (either in Bug Fixes or Changes to API)
• [ ] updated relevant tests
• [ ] updated relevant documentation
• [ ] updated relevant milestone(s)
• [ ] added relevant label(s)

[codecov[bot]]

Codecov Report

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

Project coverage is 64.92%. Comparing base (4d7c3a6) to head (7a7d955). Report is 15 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #287 +/- ## ========================================== + Coverage 64.84% 64.92% +0.08% ========================================== Files 103 104 +1 Lines 5694 5707 +13 ========================================== + Hits 3692 3705 +13 Misses 2002 2002 ```

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[zacharyburnett]

I was wondering why my batchpr script didn't make a PR for stdatamodels like it did for everything else, but then I realized I had typed it as spacetelescope/stadamodels in the list, so it just silently failed 😂