chore: drop python 3.7

[mayeut]

With #455 going in, the next release will be a major one, we might as well drop python 3.7 (EOL) at the same time.

[codecov]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (3636dad) 92.05% compared to head (4bbcb83) 92.04%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #457      +/-   ##
==========================================
- Coverage   92.05%   92.04%   -0.02%     
==========================================
  Files          22       22              
  Lines        1246     1244       -2     
  Branches      299      298       -1     
==========================================
- Hits         1147     1145       -2     
  Misses         56       56              
  Partials       43       43              

Files	Coverage Δ
src/auditwheel/lddtree.py	89.80% <100.00%> (ø)
src/auditwheel/main.py	100.00% <100.00%> (ø)
src/auditwheel/wheel_abi.py	97.01% <100.00%> (ø)

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