fix: drop one arg parse shortcut

[henryiii]

This removes the one arg unicode-aware non-standard shortcut.

Two more things to look at before release:

• How does our unicode support work with wmain? That's the "correct" way to do unicode on Windows.
• What happens if someone doesn't expect / want unicode and you prepare for unicode? Is it better or worse that if you didn't prepare for it?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (20de8b7) 100.00% compared to head (6a62480) 100.00%.

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #987   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           18        17    -1     
  Lines         4573      4546   -27     
=========================================
- Hits          4573      4546   -27     

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