textproc/py-readchar: Update 4.2.1 => 4.2.2, take maintainership

Changelog:

• Fix pytest 9 compatibility.
• Add Android as a supported platform.

https://github.com/magmax/python-readchar/releases/tag/v4.2.2

• Remove unnecessary USES=dos2unix.
• Fix warnings from portclippy.

PR: 297766
Sponsored by: UNIS Labs
Co-authored-by: Vladimir Druzenko <vvd@FreeBSD.org>