Fix dev installs

[ivirshup]

• Closes Tests fail with pytest 8.1 when a data dir exists #2993
• Tests included or not required because: fixing dev install

• Release notes not necessary because:

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 75.50%. Comparing base (4d82db0) to head (999e56b).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2994      +/-   ##
==========================================
- Coverage   75.51%   75.50%   -0.01%     
==========================================
  Files         117      117              
  Lines       12955    12944      -11     
==========================================
- Hits         9783     9774       -9     
+ Misses       3172     3170       -2     

Files	Coverage Δ
scanpy/testing/_pytest/__init__.py	89.47% <ø> (+1.23%)	⬆️