Use Python3 `super()` throughout `torch.testing.` (#37024)
Summary:
Hattip to ezyang
Pull Request resolved: https://github.com/pytorch/pytorch/pull/37024
Differential Revision: D21173244
Pulled By: malfet
fbshipit-source-id: 7079703e28777d873f69bf9fd4dcbad8d53a2682
