Replace getID3 with ffprobe #1181
Description
We currently use getID3 to extract metadata and bitrate from uploaded songs, which can only handle certain types of files -which is where the file type restriction comes from.
Switch to using ffmpeg/ffprobe, which can in theory handle any file type.
This would not be adding a dependency, as we already have ffmpeg to handle the transcoding - in fact it would be removing one.