new release v0.4.0 adding perceptual weighting, distance arguments, a…

…nd fixes to DC loss

Move librosa and scipy to optional dependancies

SDR loss stability fix

new release with filterbank device fix

rework of STFTLoss and some minor bug fixes

make the test pypi run only on tag

updating version to v0.1.5

updating version to v0.1.5

update verion in setup.py

first version of the sum and difference STFT Loss