www/yt-dlp: Make py-SecretStorage an optional port dependency
py-SecretStorage pulls a lot of dependencies for a small
optional feature in yt-dlp.
The upstream merged the PR that also makes SecretStorage optional:
https://github.com/yt-dlp/yt-dlp/pull/8585
PR: 275196
Submitted by: Helge Oldach <freebsd@oldach.net> (initial version)