audio/musicpd: Update to upstream release 0.23
Details:
- Big release with new features and fixes, see: https://raw.githubusercontent.com/MusicPlayerDaemon/MPD/v0.23/NEWS including:
- New plugins for OPENMTP, PIPEWIRE (both as non-default OPTIONS), and snapcast (later enabled by default, since no new LIB_DEPENDS).
- Support for libnpupnp via UPNP OPTION.
- DSD over PCM playback via native OSS output.
- PROXY requires mpd 0.20 or later now. This might be a regression for some users' use cases, hence no merge to quarterly yet.
- While one it: Fix search paths for config files when not using the rc script in the man pages.