fix(ci): actually run tests on multiple Python versions

[codecov[bot]]

Codecov Report

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

Project coverage is 80.96%. Comparing base (988011f) to head (9668538).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #493 +/- ## ======================================= Coverage 80.96% 80.96% ======================================= Files 23 23 Lines 1886 1886 ======================================= Hits 1527 1527 Misses 359 359 ```

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