Bit Depth forced @12 bit when input is APR 4x XQ

This may be an intended choice for some reason I am not aware of, but I wanted to signal that once input video is Apple ProRes 4444 XQ, available encoding 'Bit Depth' is only 12 bit (`yuv420p12le`), so as a side consequence I can even choose `main10` as Profile, but that will generate an error when calling ffmpeg.

Encoding @ 12 bit, furthermore, seems to kill HDR10+ when providing an external JSON sidecar: the rendered file will read in MediaInfo "_SMPTE ST 2086, HDR10 compatible_" without the additional specification "_SMPTE ST 2094 App 4, Version 1, HDR10+ Profile A compatible_", which I obtain when calling ffmpeg from Command Line by simply replacing `-pix_fmt yuv420p12le` with `-pix_fmt yuv420p10le` (and adding `-profile:v main10`).

Ps: ran into this amazing tool yesterday, thank you for your work!