Eliminate pycodestyle warnings

[martinholmer]

Non-substantive, cosmetic changes in Python code to eliminate pycodestyle warnings.
This work used the newest version of pycodestyle: release 2.12.1.
The .py files in the taxcalc/validation directory tree were excluded from this work.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.42%. Comparing base (b3f5eb5) to head (d0aa3bc).
Report is 5 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2858   +/-   ##
=======================================
  Coverage   99.42%   99.42%           
=======================================
  Files          13       13           
  Lines        2625     2625           
=======================================
  Hits         2610     2610           
  Misses         15       15           

Flag	Coverage Δ
unittests	99.42% <ø> (ø)

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Files with missing lines	Coverage Δ
taxcalc/calculator.py	100.00% <ø> (ø)