PR: Fix some issues related to wstring creation in winpty spawn arguments

[andfoy]

No description provided.

[codecov-commenter]

Codecov Report

Merging #13 (f1e95f1) into main (7158431) will decrease coverage by 0.14%.
The diff coverage is 64.70%.

@@            Coverage Diff             @@
##             main      #13      +/-   ##
==========================================
- Coverage   74.64%   74.50%   -0.15%     
==========================================
  Files           8        8              
  Lines        1203     1208       +5     
==========================================
+ Hits          898      900       +2     
- Misses        305      308       +3     

Flag	Coverage Δ
unittests	74.50% <64.70%> (-0.15%)	⬇️

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Impacted Files	Coverage Δ
src/pty/winpty/pty_impl.rs	76.70% <64.70%> (-1.08%)	⬇️

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