[Notice] Intent to drop support for Python 2.7 + Torch 1.1.0 + TF 1.12.0

[VivekPanyam]

Python 2.7 reached end of life on January 1st, 2020 (~1.5 years ago). We should probably drop support for it.

Please comment here if you still have a Python 2.7 usecase that needs more time to upgrade.