Clean up some type annotations in caffe2/torch/quantization (#49942)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/49942
Upgrades type annotations from Python2 to Python3
Test Plan: Sandcastle tests
Reviewed By: vkuzo
Differential Revision: D25717551
fbshipit-source-id: 1b63dc485ecf6641641b05f7ce095ae1d2d87346
