[numpy] `torch.exp{2, m1}`: promote integer inputs to float (#48926)
Summary:
Reference: https://github.com/pytorch/pytorch/issues/42515
Pull Request resolved: https://github.com/pytorch/pytorch/pull/48926
Reviewed By: zhangguanheng66
Differential Revision: D25392344
Pulled By: mruberry
fbshipit-source-id: ddbabcfd58cc4c944153b1a224cc232efa022104
