Fix few remaining lint issues

[peterMuriuki]

• update readme with command to make commit hook active
• Deprecate flake8 in favor of ruff.
• Move lint checker to ci; remove test suite used previously

[codecov-commenter]

Codecov Report

Merging #385 (dee1ab0) into master (36cba29) will not change coverage. The diff coverage is 0.00%.

@@           Coverage Diff           @@
##           master     #385   +/-   ##
=======================================
  Coverage   67.30%   67.30%           
=======================================
  Files         123      123           
  Lines        7491     7491           
=======================================
  Hits         5042     5042           
  Misses       2449     2449           

Impacted Files	Coverage Δ
...ally/views/reports/administrative_areas_reports.py	33.43% <0.00%> (ø)

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