removal proposal: net/youtube-dl

[Greg Troxel <gdt%lexort.com@localhost>]

I see that youtube-dl uses a distfile from 2021.12.17.  yt-dlp is the
apparent (sole or at least main) successor fork, with a release/distfile
that's less than 30 days old.

I'm not super clear on the details, but my impression is that youtube-dl
from 2021 is extremely unlikely to do anything useful in 2026.

I therefore suggest that there are zero users of youtube-dl and that it
should be deleted.  I'll delete no earlier than 7/11 12Z unless there
are objections.