Changed value constraint of exponential dist (#67184)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/67183.
cc fritzo neerajprad alicanb nikitaved
Pull Request resolved: https://github.com/pytorch/pytorch/pull/67184
Reviewed By: ejguan
Differential Revision: D32114661
Pulled By: neerajprad
fbshipit-source-id: ea23e59f38a23a7b0bab4fbbd98ae3feba468b9c
