Clean up some type annotations in caffe2/contrib/aten/gen_op (#49945)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/49945
Upgrades type annotations from Python2 to Python3
Test Plan: Sandcastle tests
Reviewed By: xush6528
Differential Revision: D25717502
fbshipit-source-id: 718d93e8614e9d050f4da1c6bd4ac892bab98154
