Fix test coverage

[dstansby]

Fixes #3333 (hopefully). To prevent me having to copy/paste environment variables for four different hatch environments, I also de-duplicated the configuration of the test environments. 🤞 this works fine, happy to revert the de-duplication and do a copy-and-paste job if folks would prefer that to keep things a bit simpler.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.40%. Comparing base (1858af1) to head (a609d06).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #3334       +/-   ##
===========================================
+ Coverage   60.69%   94.40%   +33.70%     
===========================================
  Files          78       78               
  Lines        9401     9401               
===========================================
+ Hits         5706     8875     +3169     
+ Misses       3695      526     -3169     

see 66 files with indirect coverage changes

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