multimedia/mpv-mpris: update to 1.0

Changelog:

• rename album fields to match MusicBrainz internal names by @tpeacock19 in #81
• Fix string leaks in property change handler by @mia-0 in #84
• Makefile: Allow to append CFLAGS / LDFLAGS from environment. by @olifre in #87
• Do not use the default GMainContext by @gnome-mpv in #88