Fix error in publish_model.py for pt>=1.6

[ckkelvinchan]

According to the official PyTorch docs

The 1.6 release of PyTorch switched torch.save to use a new zipfile-based file format. torch.load still retains the 
ability to load files in the old format. If for any reason you want torch.save to use the old format, pass the kwarg 
_use_new_zipfile_serialization=False.

As a result, when using PyTorch version>=1.6 to publish models, errors occur when loading weights from URL. This PR fixes this error by adding _use_new_zipfile_serialization=False for torch.__version__ >= '1.6'

[codecov]

Codecov Report

Merging #291 (ae0fb3d) into master (3cfdd8f) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #291   +/-   ##
=======================================
  Coverage   80.54%   80.54%           
=======================================
  Files         162      162           
  Lines        8091     8091           
  Branches     1192     1192           
=======================================
  Hits         6517     6517           
  Misses       1429     1429           
  Partials      145      145           

Flag	Coverage Δ
unittests	80.54% <ø> (ø)

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