Use hypothesis to generate seed (#36860)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/36860
att
Test Plan:
```
buck test mode/dev //caffe2/caffe2/contrib/fakelowp/test:test_batchnorm_nnpi_fp16nnpi -- 'test_bn \(caffe2\.caffe2\.contrib\.fakelowp\.test\.test_batchnorm_nnpi_fp16\.BatchnormTest\)'
```
Reviewed By: hyuen
Differential Revision: D21085268
fbshipit-source-id: becc25d6e8841dc25842d9397ecf500f4da6d2f7
