adjust to new location for scanpy plotting utils

[grst]

Closes #729

• CHANGELOG.md updated
• Tests added (For bug fixes or new features)
• Tutorial updated (if necessary)

[codecov]

Codecov Report

❌ Patch coverage is 52.94118% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.18%. Comparing base (dae3334) to head (484aee0).

Files with missing lines	Patch %	Lines
src/scirpy/pl/_clonotypes.py	53.84%	6 Missing ⚠️
src/scirpy/pl/styling.py	50.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #730      +/-   ##
==========================================
- Coverage   78.31%   78.18%   -0.14%     
==========================================
  Files          51       51              
  Lines        4607     4620      +13     
==========================================
+ Hits         3608     3612       +4     
- Misses        999     1008       +9     

Files with missing lines	Coverage Δ
src/scirpy/pl/styling.py	91.52% <50.00%> (-3.12%)	⬇️
src/scirpy/pl/_clonotypes.py	86.10% <53.84%> (-1.62%)	⬇️

... and 1 file with indirect coverage changes

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[grst]

remaining failures are due to issues with the latest numba RC