Fix whitespace insensitive check triggering on tabs

[robsdedude]

This amends #898 as tabs (\t) are also considered whitespace in Python.

Found while working on #1966

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.19%. Comparing base (17746ba) to head (3d75057).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2437   +/-   ##
=======================================
  Coverage   99.19%   99.19%           
=======================================
  Files          40       40           
  Lines        3090     3090           
  Branches      680      680           
=======================================
  Hits         3065     3065           
  Misses         14       14           
  Partials       11       11           

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[DanielNoord]

Nice job! Again, only one a comment about the typing in the test.

[robsdedude]

Type annotated and squashed. Ready for another review @DanielNoord

[DanielNoord]

Thanks for taking the time to fix that annotation!