Also switch the upstream repository from github to git.sr.ht, since the
project has been moved to sourcehut.
Signed-off-by: Rouven Czerwinski <rouven@czerwinskis.de>
After making `ffmpeg` point to the latest `ffmpeg_4`, all packages that
used `ffmpeg` without requiring a specific version now use ffmpeg_3
explicitly so they shouldn't change.