[caffe2] Remove python2 from operator_test (#33977)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/33977
Removing python2 from operator_test so we can retire python2 support for PyTorch.
Test Plan: waitforsandcastle
Reviewed By: seemethere
Differential Revision: D20129500
fbshipit-source-id: d4c82e4acfc795be9bec6a162c713e37ffb9f5ff
