Migrate to ruff

[wRAR]

This keeps the % string formatting, as I think including the changes here complicate the diff review.

[codecov]

Codecov Report

Attention: Patch coverage is 96.61017% with 4 lines in your changes missing coverage. Please review.

Project coverage is 96.09%. Comparing base (ec4d1ea) to head (65d5b7d).
Report is 8 commits behind head on master.

Files with missing lines	Patch %	Lines
cssselect/parser.py	96.38%	1 Missing and 2 partials ⚠️
cssselect/xpath.py	97.14%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #150      +/-   ##
==========================================
+ Coverage   95.49%   96.09%   +0.59%     
==========================================
  Files           3        3              
  Lines         910      896      -14     
  Branches      161      142      -19     
==========================================
- Hits          869      861       -8     
+ Misses         24       14      -10     
- Partials       17       21       +4     

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