Upgrade to TensorFlow 2.0 (or not?)

[JRMeyer]

I'm getting some warnings about TF contrib being depreciated... it's not obvious to me that the repo should be upgraded to TF2.0, but it should be considered.

(venv) josh@thor:~/git/nonparaSeq2seqVC_code/pre-train$ bash run.sh 
WARNING:tensorflow:
The TensorFlow contrib module will not be included in TensorFlow 2.0.
For more information, please see:
  * https://github.com/tensorflow/community/blob/master/rfcs/20180907-contrib-sunset.md
  * https://github.com/tensorflow/addons
  * https://github.com/tensorflow/io (for I/O related ops)
If you depend on functionality not listed there, please file an issue.

[jxzhanggg]

This code basiclly rely on PyTorch. The tensorflow package is only used for creating hparams. Upgrading to tensorflow 2.0 will not be necessary.