fix np str repr

[Zethson]

• Deprecates Python 3.9 which is EOL. To be honest, I would jump immediately to 3.11+ (spec-0) or even 3.12+ (spec-0 in 2 months)
• Fixes Invalid lineage name XYZ. Valid names are [np.str_('4'), np.str_('0_1'), np.str_('0_2')]. #1261

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.55%. Comparing base (ce69c5f) to head (bcb3450).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1268      +/-   ##
==========================================
- Coverage   80.58%   80.55%   -0.04%     
==========================================
  Files          51       51              
  Lines        8618     8618              
  Branches     1491     1491              
==========================================
- Hits         6945     6942       -3     
- Misses       1095     1097       +2     
- Partials      578      579       +1     

Files with missing lines	Coverage Δ
src/cellrank/_utils/_lineage.py	84.65% <100.00%> (ø)

... and 1 file with indirect coverage changes

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[michalk8]

LGTM, thanks a lot!