Add test dependencies to CONTRIBUTING.md (#41799)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/41799
Reviewed By: zhangguanheng66
Differential Revision: D22645323
Pulled By: zou3519
fbshipit-source-id: 0a695bffb57b29024461472dd1c8518a9a0d1d3b
