chore: Self usage

[henryiii]

Using self with mypy 1.0. Not requiring it at runtime. Typing extensions is required for <3.8 still, since it's used at runtime. Also enabling the shiny new --show-fixes in Ruff! :)

[codecov]

Codecov Report

Merging #199 (5b1c3a8) into main (fa9f975) will decrease coverage by 0.03%.
The diff coverage is 91.66%.

❗ Current head 5b1c3a8 differs from pull request most recent head c37eb10. Consider uploading reports for the commit c37eb10 to get more accurate results

@@            Coverage Diff             @@
##             main     #199      +/-   ##
==========================================
- Coverage   89.49%   89.46%   -0.03%     
==========================================
  Files          45       45              
  Lines        2046     2050       +4     
==========================================
+ Hits         1831     1834       +3     
- Misses        215      216       +1     

Impacted Files	Coverage Δ
src/scikit_build_core/_compat/typing.py	92.85% <85.71%> (-7.15%)	⬇️
src/scikit_build_core/build/_wheelfile.py	99.29% <100.00%> (-0.01%)	⬇️
src/scikit_build_core/builder/wheel_tag.py	83.33% <100.00%> (-0.23%)	⬇️
src/scikit_build_core/cmake.py	82.26% <100.00%> (ø)

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