multimedia/smplayer: update to 23.6.0

* Fix the issue of YouTube playback limited to 720p.
* Update mpv and mplayer.
* New option in preferences to keep the playback speed for all videos.
* Fix the AppImage package.
* Other bug fixes.
Changelog: https://www.smplayer.info/changes

Approved by:	arrowd (mentor, implicit)
MFH:		2023Q3

(cherry picked from commit c24b184b)