ffmpeg: MP3 format crash with Deesing

[Pendrokar]

By default, the Deesing setting is set to 0.1. This makes ffmpeg go into a fatal error and display the pop-up:
Output ./resources/app/output/temp-16335802487988227_ffmpeg.mp3 same as Input #0 - exiting FFmpeg cannot edit existing files in-place.

This part of the code is at fault, as it expects WAV.
https://github.com/DanRuta/xVA-Synth/blob/master/python/audio_post.py#L81

[Pendrokar]

Workaround: Either use WAV format or set Deesing to zero within xVASynth settings.

[Pendrokar]

audio_post.py seems to require a development environment for code changes to take affect.