add support for pickle v4 (#70642)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/70642
Review history on https://github.com/pytorch/pytorch/pull/70014
Test Plan: Imported from OSS
Reviewed By: suo
Differential Revision: D33414364
Pulled By: PaliC
fbshipit-source-id: 7e7ed491c6f16d4fac3a03f7e403935823c03aa6
