Eliminate pylint warnings

[martinholmer]

Non-substantive, cosmetic changes in Python code to eliminate pylint warnings.
This work used the newest version of pylint: release 3.3.3.
The .py files in the taxcalc/validation and docs/guide directory trees were excluded from this work.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.96%. Comparing base (17bd940) to head (3223cdd).
Report is 49 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2859      +/-   ##
==========================================
+ Coverage   99.42%   99.96%   +0.53%     
==========================================
  Files          13       13              
  Lines        2625     2618       -7     
==========================================
+ Hits         2610     2617       +7     
+ Misses         15        1      -14     

Flag	Coverage Δ
unittests	99.96% <100.00%> (+0.53%)	⬆️

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

Files with missing lines	Coverage Δ
taxcalc/calculator.py	100.00% <100.00%> (ø)
taxcalc/consumption.py	100.00% <100.00%> (ø)
taxcalc/data.py	99.25% <100.00%> (ø)
taxcalc/decorators.py	100.00% <100.00%> (ø)
taxcalc/growdiff.py	100.00% <100.00%> (ø)
taxcalc/growfactors.py	100.00% <100.00%> (ø)
taxcalc/parameters.py	100.00% <100.00%> (ø)
taxcalc/policy.py	100.00% <100.00%> (ø)
taxcalc/records.py	100.00% <ø> (ø)
taxcalc/taxcalcio.py	100.00% <100.00%> (ø)
... and 1 more