move torch.testing from prototype to beta (#69668)
Summary:
cc brianjo mruberry
Pull Request resolved: https://github.com/pytorch/pytorch/pull/69668
Reviewed By: albanD
Differential Revision: D33028213
Pulled By: mruberry
fbshipit-source-id: 3316b887d4c322cc1262feee651464da4124a6de
