add __init__.py to utils

[joeddav]

Adds __init__.py to the utils dir introduced in #6434, which caused a namespace issues breaking imports in some cases. Mentioned in #6752.

To reproduce, pip install from source without the editable -e flag.

>>> from transformers import pipeline
...
~/.virtualenvs/transformers/lib/python3.7/site-packages/transformers/file_utils.py in <module>
---> 32 from .utils import logging
ModuleNotFoundError: No module named 'transformers.utils'

[codecov]

Codecov Report

Merging #6754 into master will increase coverage by 0.42%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #6754      +/-   ##
==========================================
+ Coverage   79.02%   79.45%   +0.42%     
==========================================
  Files         157      157              
  Lines       28479    28479              
==========================================
+ Hits        22505    22627     +122     
+ Misses       5974     5852     -122     

Impacted Files	Coverage Δ
src/transformers/tokenization_mbart.py	56.25% <0.00%> (-39.07%)	⬇️
src/transformers/tokenization_xlnet.py	66.66% <0.00%> (-23.43%)	⬇️
src/transformers/tokenization_dpr.py	57.65% <0.00%> (+4.50%)	⬆️
src/transformers/tokenization_xlm.py	82.93% <0.00%> (+66.66%)	⬆️

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[thomwolf]

Ok!

[abelriboulot]

This is great! I can confirm this fixes it. It would be good to merge it fast as the current master fails.