emulators/mgba: update to 0.10.3

Emulation fixes:
 - ARM: Remove obsolete force-alignment in `bx pc` (fixes mgba.io/i/2964)
 - ARM: Fake bpkt instruction should take no cycles (fixes mgba.io/i/2551)
 - GB Audio: Fix channels 1/2 staying muted if restarted after long silence
 - GB Audio: Fix channel 1 restarting if sweep applies after stop (fixes mgba.io/i/2965)
 - GB Audio: Fix restarting envelope when writing to register (fixes mgba.io/i/3067)
 - GB Audio: Improve "zombie mode" emulation in CGB mode (fixes mgba.io/i/2029)
 - GB I/O: Read back proper SVBK value after writing 0 (fixes mgba.io/i/2921)
 - GB SIO: Disabling SIO should cancel pending transfers (fixes mgba.io/i/2537)
 - GBA Audio: Fix sample timing drifting when changing sample interval
 - GBA Audio: Fix initial channel 3 wave RAM (fixes mgba.io/i/2947)
 - GBA Audio: Fix sample position issues when rate changes (fixes mgba.io/i/3006)
 - GBA GPIO: Fix tilt scale and orientation (fixes mgba.io/i/2703)
 - GBA BIOS: Fix clobbering registers with word-sized CpuSet
 - GBA SIO: Fix normal mode SI/SO semantics (fixes mgba.io/i/2925)
Other fixes:
 - GB: Fix applying a patch that changes the cartridge mapper (fixes mgba.io/i/3077)
 - GBA Savedata: Fix crash when resizing flash save games for RTC data
 - mGUI: Fix cases where an older save state screenshot would be shown (fixes mgba.io/i/2183)
 - Qt: Re-enable sync for multiplayer windows that aren't connected (fixes mgba.io/i/2974)
 - Qt: Fix mute settings not being loaded on setting screen (fixes mgba.io/i/2990)
 - Qt: Fix screen freezing on macOS after closing save state window (fixes mgba.io/i/2885)
 - Vita: Fix camera setting not appearing (fixes mgba.io/i/3012)
Misc:
 - mGUI: Persist fast forwarding after closing menu (fixes mgba.io/i/2414)
 - Qt: Add exporting of SAV + RTC saves from Save Converter to strip RTC data
 - VFS: Use anonymousMemoryMap for large 7z allocations (fixes mgba.io/i/3013)