Checkout pytorch_sphinx_theme with https. (#18859)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/18859
ghimport-source-id: fbbcb8a2dd9c9f0a317de489b6bbb83e9071a7d8
Differential Revision: D14801989
Pulled By: ezyang
fbshipit-source-id: a9bc02e1383adafcac01994e6346b28551d95c71
