Add X-UMX baseline

Fix evaluation

Add better lower baseline

See merge request sony/music-demixing-challenge-starter-kit!5

simplify torch hub loading

See merge request sony/music-demixing-challenge-starter-kit!7

Add resampler to baseline

See merge request sony/music-demixing-challenge-starter-kit!6

add audio apt deps

See merge request sony/music-demixing-challenge-starter-kit!4

[Continuation of #1] Add umx predictor

See merge request sony/music-demixing-challenge-starter-kit!3

# Conflicts:
#   requirements.txt

Update README.md

See merge request sony/music-demixing-challenge-starter-kit!2