multimedia/mpv: update to 0.31.0
- Adjust ZIMG description after https://github.com/mpv-player/mpv/commit/13fe87f66b2c
- Adjust TEST after https://github.com/mpv-player/mpv/commit/fb5689631993
- Drop TEST fix for i386 after https://github.com/mpv-player/mpv/commit/293dfc782552
Changes: https://github.com/mpv-player/mpv/releases/tag/v0.31.0
Reported by: GitHub (watch releases)