Fix pandas/PETSc issues

[michalk8]

TODOs:

• fix the rest of the failing tests
• fix PETSc >= 3.20
• fix some warnings in tests

closes #1128
closes #1134

[codecov]

Codecov Report

Merging #1136 (8043c9c) into main (f3a6a0e) will increase coverage by 1.27%.
The diff coverage is 74.35%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1136      +/-   ##
==========================================
+ Coverage   79.37%   80.65%   +1.27%     
==========================================
  Files          51       51              
  Lines        8483     8491       +8     
  Branches     1645     2218     +573     
==========================================
+ Hits         6733     6848     +115     
+ Misses       1207     1101     -106     
+ Partials      543      542       -1     

Files	Coverage Δ
src/cellrank/kernels/_precomputed_kernel.py	94.11% <100.00%> (ø)
src/cellrank/pl/_aggregate_fate_probs.py	87.29% <100.00%> (ø)
src/cellrank/pl/_heatmap.py	96.12% <100.00%> (ø)
src/cellrank/_utils/_colors.py	81.20% <66.66%> (ø)
src/cellrank/_utils/_lineage.py	84.94% <94.44%> (+0.04%)	⬆️
src/cellrank/_utils/_linear_solver.py	93.58% <80.00%> (+52.50%)	⬆️
.../cellrank/estimators/mixins/_fate_probabilities.py	83.75% <50.00%> (ø)
src/cellrank/estimators/terminal_states/_gpcca.py	78.21% <75.00%> (ø)
src/cellrank/kernels/_utils.py	63.41% <80.00%> (ø)
src/cellrank/kernels/utils/_random_walk.py	77.41% <75.00%> (+0.14%)	⬆️
... and 7 more

... and 5 files with indirect coverage changes