audio/musicpd: Update to upstream release 0.22.8.
Details:
- Upstream release, see https://raw.githubusercontent.com/MusicPlayerDaemon/MPD/v0.22.8/NEWS
- Fixes a regression (crash in the "albumart" command)
MFH: 2021Q2
(cherry picked from commit c194689f693785f04f66ccb5a813d849b329f2da)