CompatHelper: bump compat for Trixi to 0.9, (keep existing compat)

[github-actions[bot]]

This pull request changes the compat entry for the Trixi package from 0.7, 0.8 to 0.7, 0.8, 0.9. This keeps the compat entries for earlier versions.

Note: I have not tested your package with this new compat entry. It is your responsibility to make sure that your package tests pass before you merge this pull request.

[codecov[bot]]

Codecov Report

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

Project coverage is 81.78%. Comparing base (dabbf64) to head (85f29a1). Report is 1 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #41 +/- ## ======================================= Coverage 81.78% 81.78% ======================================= Files 8 8 Lines 829 829 ======================================= Hits 678 678 Misses 151 151 ```

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