[cleanup] Misc cleanup (#2173)

Changelog.md

README.md

devscripts/bash-completion.py

devscripts/fish-completion.py

devscripts/make_lazy_extractors.py

devscripts/zsh-completion.py

test/test_overwrites.py

yt_dlp/YoutubeDL.py

yt_dlp/compat.py

yt_dlp/extractor/abematv.py

yt_dlp/extractor/sonyliv.py

yt_dlp/postprocessor/sponsorblock.py

yt_dlp/utils.py