Clean up future imports for Python 2 (#53349)
Summary:
See https://github.com/pytorch/pytorch/issues/42919
Pull Request resolved: https://github.com/pytorch/pytorch/pull/53349
Reviewed By: malfet
Differential Revision: D27039089
Pulled By: bugra
fbshipit-source-id: 8063dc184248604506a8dbb1bcb73da8ec85bb18
