ci: use macos-13 instead of macos-latest for python 3.9

[dkrako]

fixes #723

[codecov[bot]]

Codecov Report

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

Project coverage is 100.00%. Comparing base (115a9b3) to head (8ab71d0).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #724 +/- ## ========================================= Coverage 100.00% 100.00% ========================================= Files 60 60 Lines 2757 2757 Branches 709 709 ========================================= Hits 2757 2757 ```

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