Fix several DeprecationWarning: invalid escape sequence (#15733)
Summary:
Hello,
This is a little patch to fix `DeprecationWarning: invalid escape sequence`.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15733
Differential Revision: D13587291
Pulled By: soumith
fbshipit-source-id: ce68db2de92ca7eaa42f78ca5ae6fbc1d4d90e05
