chore(types): add py.typed marker

[ArmaanjeetSandhu]

Adds a PEP 561 py.typed marker file to the package, in reference to #1090

To confirm the marker is present in the installed package, run:

uv run python -c "import codecarbon; import pathlib; p = pathlib.Path(codecarbon.__file__).parent / 'py.typed'; print(p, p.exists())"

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.19%. Comparing base (0eee57c) to head (691d5e9).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1093   +/-   ##
=======================================
  Coverage   78.19%   78.19%           
=======================================
  Files          38       38           
  Lines        3636     3636           
=======================================
  Hits         2843     2843           
  Misses        793      793           

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[benoit-cty]

Thanks, I did not know about py.typed.