Fix torch.hub for new zipfile format. (#42333)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/42239
Pull Request resolved: https://github.com/pytorch/pytorch/pull/42333
Reviewed By: VitalyFedyunin
Differential Revision: D23215210
Pulled By: ailzhang
fbshipit-source-id: 161ead8b457c11655dd2cab5eecfd0edf7ae5c2b
