[ZeroRedundancyOptimizer] Minor stub fix (#53165)
Summary:
Not sure how important that is
Tied to https://github.com/pytorch/pytorch/issues/53108
Pull Request resolved: https://github.com/pytorch/pytorch/pull/53165
Reviewed By: albanD
Differential Revision: D26781956
Pulled By: blefaudeux
fbshipit-source-id: b7daca0ea95be190a5ffeae12123e301204ed4eb
