Retry pip install to make pytorch rocm CI more stable (#21895)
Summary:
pip install randomly core dumps, examples:
https://ci.pytorch.org/jenkins/job/pytorch-builds/job/py2-clang7-rocmdeb-ubuntu16.04-test/25720//console
https://ci.pytorch.org/jenkins/job/pytorch-builds/job/py2-clang7-rocmdeb-ubuntu16.04-test/25723//console
Pull Request resolved: https://github.com/pytorch/pytorch/pull/21895
Differential Revision: D15873197
Pulled By: bddppq
fbshipit-source-id: 2c967bc0a47bef9d3f7af83e99514c93b54e353f
