Add py.typed file and Typing :: Typed classifier

[hugovk]

Following #183, I think we can declare this project as typed, so dependents can stop relying on the third-party wcwidth-stubs?

[codspeed-hq]

CodSpeed Performance Report

Merging this PR will not alter performance

_{Comparing hugovk:py.typed (2e17571) with master (4738d79)}

Summary

✅ 38 untouched benchmarks

[jquast]

Yes, I think so... does this mean I have to release another version to pypi for this to work?

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (4738d79) to head (2e17571).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##            master      #184   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           13        13           
  Lines          604       604           
  Branches       145       145           
=========================================
  Hits           604       604           

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[hugovk]

Yes, but it's not urgent.

[trim21]

finally

[trim21]

I'm going to add partial to wcwidth-stubs/py.typed and remove all pyi to make wcwidth-stubs a nope stubs.