Refactoring formatter, linter, and checker

[kotarot]

Update line length and introducing flake8-bugbear.

[codecov]

Codecov Report

Merging #24 (9de81ff) into main (9d6343a) will increase coverage by 0.05%.
The diff coverage is 100.00%.

❗ Current head 9de81ff differs from pull request most recent head e3fe427. Consider uploading reports for the commit e3fe427 to get more accurate results

@@            Coverage Diff             @@
##             main      #24      +/-   ##
==========================================
+ Coverage   92.10%   92.16%   +0.05%     
==========================================
  Files           8        8              
  Lines         266      268       +2     
==========================================
+ Hits          245      247       +2     
  Misses         21       21              

Flag	Coverage Δ
unittests	92.16% <100.00%> (+0.05%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
rectangle_packing_solver/sequence_pair.py	81.91% <ø> (ø)
rectangle_packing_solver/__init__.py	100.00% <100.00%> (ø)
rectangle_packing_solver/solver.py	97.26% <100.00%> (+0.07%)	⬆️

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