MAINT: compatibility, warning cleanup, test lint

[martinfleis]

I wanted to primarily cleanup warnings from our CI. So some changes related to that, some changes related to compatibility (FutureWarning removal), plus linting of tests which was for some reason disabled.

[codecov]

Codecov Report

Attention: Patch coverage is 98.18182% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 97.8%. Comparing base (4037c70) to head (9d1d944).
Report is 18 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##            main    #574     +/-   ##
=======================================
+ Coverage   97.4%   97.8%   +0.4%     
=======================================
  Files         26      37     +11     
  Lines       4328    5160    +832     
=======================================
+ Hits        4214    5045    +831     
- Misses       114     115      +1     

Files	Coverage Δ
momepy/coins.py	95.3% <ø> (ø)
momepy/dimension.py	98.8% <100.0%> (+<0.1%)	⬆️
momepy/functional/_elements.py	100.0% <100.0%> (ø)
momepy/functional/tests/test_elements.py	100.0% <ø> (ø)
momepy/intensity.py	99.5% <100.0%> (+<0.1%)	⬆️
momepy/preprocessing.py	93.4% <100.0%> (+0.1%)	⬆️
momepy/tests/test_dimension.py	100.0% <ø> (ø)
momepy/tests/test_distribution.py	100.0% <100.0%> (ø)
momepy/tests/test_diversity.py	100.0% <100.0%> (ø)
momepy/tests/test_elements.py	100.0% <100.0%> (ø)
... and 9 more

[jGaboardi]

One small note/clarification, but LGTM.