Update Python to 3.7 about gpu_docker

[semperstew]

The base image from which all of our images derive is tensorflow/tensorflow:[version]-gpu-py3. Our only choices of python version are 2.7 or 3.5. As it stands, the only way to upgrade to python3.7 is to hand-roll a tensorflow base image with 3.7 installed. I don't know about you, but that's not really something that I care to maintain in the long run.
@oersoy1 Are there particular features of python3.7 that you can't live without?

[oersoy1]

Nah.. I had to refactor some of my code for str formatting type of stuff.. Tensorflow.. Yuck..

[oersoy1]

Pytorch works with 3.7 and 3.6 and 3.5

[semperstew]

TF certainly works with 3.7, but they aren't shipping a prebuilt TF image with 3.7 installed (yet).

[semperstew]

Closing. Won't fix at this time.