ensure extension modules are present in built wheel

[zacharyburnett]

Resolves SCSB-149

Checklist

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

[codecov[bot]]

Codecov Report

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

Project coverage is 84.99%. Comparing base (af5aefb) to head (ccbc897). Report is 5 commits behind head on main.

:exclamation: Current head ccbc897 differs from pull request most recent head 216c0a7

Please upload reports for the commit 216c0a7 to get more accurate results.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #256 +/- ## ========================================== - Coverage 85.18% 84.99% -0.19% ========================================== Files 35 35 Lines 6797 6865 +68 ========================================== + Hits 5790 5835 +45 - Misses 1007 1030 +23 ```

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