fix: Windows double line spacing fix

[henryiii]

The current version does not work on Windows, as reported by @pfmoore in pypa/pip#9462. Files opened in text mode should not have the native line ending applied - Python normalizes this for you. Quick demo of problem:

from pathlib import Path
from os import linesep

txt = Path("tmp.txt")
with txt.open("w", encoding="utf-8") as f:
    f.writelines(f"{p}{linesep}" for p in range(3))
with txt.open(encoding="utf-8") as f:
    print(f.read())

This produces empty lines between outputs, but only Windows (due to the separator there).

Had to find and boot up an old Windows box to verify that demo. 😠

[pradyunsg]

Thanks for the PR! ^>^