Improvements and tweaks to correction process

[beveradb]

Currently the output from the correction process is good but not quite good enough for general release, even for the test track:
https://github.com/karaokenerds/python-lyrics-transcriber/releases/download/v0.12.1/ABBAUnderAttack-mp3_b5bafd91e7421f0635baa9005f5a3119.mp4

Noticeable issues include:

• Some overlapping / confusing lyrics (e.g. when there are background vocals at the same time as primary)
  • The scrolling lyrics should ideally only track the primary vocals for now; although this does inspire me that we could possible handle duets with this approach in future!
  • One approach to resolving this might be to separate the audio with a background-vocals (BVE) model first and only pass the primary vocal stem to whisper in the first place. TBD if this helps.
• One or two lines of totally unexpected lyrics; need to investigate why. I suspect these are also backing vocals which couldn't find a place.
• At least one case where there was still a misheard word left in the corrected lyrics ("shattered" vs. "flattered"); this is less critical but possibly an opportunity to tweak the prompt to give it more guidance, e.g. asking it to watch out for sound-alike words like this and correct them.

It would be good to add some more functionality to the correction method to help debug and tweak the prompt, e.g. logging changes to each segment to a file, printing / writing an overall diff of the spotify lyrics vs. the corrected lyrics, etc.