Pin fairseq version to 0.11.0 (#902)
Summary:
Recently CI is broken because fairseq updated their code to add xformers dependencies.
We should pin the fairseq verison to 0.11.0 to prevent future code breakage.
Also, add constraints to the opacus package because of https://github.com/pytorch/opacus/pull/426
Pull Request resolved: https://github.com/pytorch/benchmark/pull/902
Reviewed By: erichan1
Differential Revision: D36237766
Pulled By: xuzhao9
fbshipit-source-id: 3e1f961f3d3ce0a393663e30d6ea712bff20204c
