MNT: handle deprecation warnings seen in tests

[codecov[bot]]

Codecov Report

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

Comparison is base (cfa0958) 71.10% compared to head (e578ea9) 76.45%.

:exclamation: Current head e578ea9 differs from pull request most recent head 66b3f4c. Consider uploading reports for the commit 66b3f4c to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #67 +/- ## ========================================== + Coverage 71.10% 76.45% +5.34% ========================================== Files 4 4 Lines 308 310 +2 ========================================== + Hits 219 237 +18 + Misses 89 73 -16 ```

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[neutrinoceros]

There's one remaining warning:

DeprecationWarning: the load_module() method is deprecated and slated for removal in Python 3.12; use exec_module() instead

but I could not figure out how to implement the replacement yet (it's probably not that complicated but I'm really not familiar with loader semantics). I note however that the code still works on Python 3.12, so it's there's still time to handle it.

edit: fixed it too !