Fix encoding errors for hipify tool (#37906)
Summary:
Encoding errors occur when using anaconda python 3.6.10 to run hipify_python.py, e.g., "' ASCII 'codec can't decode byte 0xc3".
Pull Request resolved: https://github.com/pytorch/pytorch/pull/37906
Differential Revision: D21549531
Pulled By: ezyang
fbshipit-source-id: 2ffb5787e192a5c03711baa5c7e2577cb5bcab5a
