Closes #3565, https://github.com/yt-dlp/yt-dlp/issues/3514#issuecomment-1105944364

Fixes an issue in 7ab56be2

Closes #19

* And fix some existing warnings

Authored by: fstirlitz

Authored by: fstirlitz, pukkandan

Using https://github.com/PyCQA/isort

    isort -m VERTICAL_HANGING_INDENT --py 36 -l 80 --rr -n --tc .

Using https://github.com/asottile/pyupgrade

1. `__future__` imports and `coding: utf-8` were removed
2. Files were rewritten with `pyupgrade --py36-plus --keep-percent-format`
3. f-strings were cherry-picked from `pyupgrade --py36-plus`

Extractors are left untouched (except removing header) to avoid unnecessary merge conflicts

Authored by fstirlitz, pukkandan

Closes #3173

Closes #2828, closes #2734, closes #2802, closes #2937

Closes #2873

Closes #1942 #1976 #2020 #2058 #1984

Bug in ec2e44fc
Closes #2060

Closes #1448
Authored by: iw0nderhow, pukkandan

Closes #1851

[mastodon] backport 7d472bcf and 1373dde1

and some minor cleanup of docs

`-k` filters using a substring match on test name.
`-m` checks markers for an exact match.
Authored by: sulyi

Authored by: pukkandan, timethrow

https://github.com/yt-dlp/homebrew-taps
Closes: #754, #770
Authored by: nao20010128nao