Doesn't install default_configs, because of missing MANIFEST.in file

[buhrmann]

See here: https://setuptools.readthedocs.io/en/latest/userguide/datafiles.html e.g.

This also makes label-studio-transformers fail, as the first thing to do according to its README is

label-studio-ml init my-ml-backend --script models/bert_classifier.py  

which fails because it can't find the default_configs folder