Alias for `polygamma` (#59691)
Summary:
See https://github.com/pytorch/pytorch/issues/50345
cc: mruberry kshitij12345
Pull Request resolved: https://github.com/pytorch/pytorch/pull/59691
Reviewed By: gchanan
Differential Revision: D29707514
Pulled By: mruberry
fbshipit-source-id: 40c15e1fda3d9f7013977b0f36a77b228dda6aa5
