Forward fix type hint for DataLoader (#66001)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/66001
Test Plan: Imported from OSS
Reviewed By: NivekT
Differential Revision: D31340565
Pulled By: ejguan
fbshipit-source-id: d05ae42ebf93f61d781dc5d81ef0222e24f5acb3
