Handle classes with __new__ method

[cgarciae]

• Correctly handles classes that define a __new__ method.
• Fixes publish-package action.

[codecov]

Codecov Report

Merging #10 (82e3f62) into main (14dafaf) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main      #10   +/-   ##
=======================================
  Coverage   97.45%   97.45%           
=======================================
  Files           2        2           
  Lines         118      118           
=======================================
  Hits          115      115           
  Misses          3        3           

Impacted Files	Coverage Δ
simple_pytree/__init__.py	100.00% <100.00%> (ø)
simple_pytree/pytree.py	97.39% <100.00%> (ø)

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