Ruff: Stricter linting rules

[tony]

Docs:

• https://beta.ruff.rs/docs/rules/
• https://beta.ruff.rs/docs/settings/

See also: https://github.com/cihai/cihai/pull/353, https://github.com/cihai/cihai-cli/pull/295

[codecov[bot]]

Codecov Report

Merging #290 (0002f94) into master (bf5e38c) will decrease coverage by 0.31%. The diff coverage is 77.14%.

@@            Coverage Diff             @@
##           master     #290      +/-   ##
==========================================
- Coverage   70.70%   70.39%   -0.31%     
==========================================
  Files          12       12              
  Lines        1065     1064       -1     
  Branches      196      193       -3     
==========================================
- Hits          753      749       -4     
- Misses        284      287       +3     
  Partials       28       28              

Impacted Files	Coverage Δ
src/unihan_etl/_internal/app_dirs.py	96.42% <ø> (ø)
src/unihan_etl/options.py	5.00% <ø> (ø)
src/unihan_etl/pytest_plugin.py	28.37% <0.00%> (ø)
src/unihan_etl/util.py	51.78% <ø> (ø)
tests/test_expansion.py	98.52% <50.00%> (ø)
src/unihan_etl/core.py	60.63% <70.58%> (-0.84%)	:arrow_down:
src/unihan_etl/expansion.py	61.00% <100.00%> (-0.52%)	:arrow_down:
tests/_internal/test_app_dirs.py	90.00% <100.00%> (ø)
tests/test_unihan.py	96.55% <100.00%> (ø)

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