audio/rsgain: Update to 3.5.1

This is a patch release to fix a critical bug impacting Opus files with
3 or more audio channels. This bug is related to the CRC32 calculation
in the Ogg header and may cause the file to become unplayable. Users
are strongly recommended to upgrade immediately.

Any files that have been impacted by this bug can be repaired by
scanning them again with this version.

https://github.com/complexlogic/rsgain/releases/tag/v3.5.1

MFH: 2024Q2