Split newlines only at Python universal newlines (LF, CRLF, CR)

[akaihola]

Fixes #86 and akaihola/darker#768.

• Review Update to Pylint 3.3.0+ #88
• Merge Update to Pylint 3.3.0+ #88
• Rebase this PR on main
• Solve failing unit tests (also on darker.verification.NotEquivalentError: nonascii2.py (IPython test file) darker#768)

[akaihola]

@Carreau here's the fix on the Darkgraylib side to your bug report in akaihola/darker#768. I invited you as a collaborator on this repo, too – would you like to review?

[Carreau]

Thanks !

[Carreau]

Thanks ! I've fixed the upstream repo in IPython and it was really an edge case, but thenks for looking into it and fixing. Happy new year also.

[Carreau]

(I'm not sure about the policy here, but I think we can ignore the pyupgrade recommendation or just apply them, both are fine with me).