DOC: remove git stamp from release documentation version (#58486)
Summary:
CI built the documentation for the recent 1.9.0rc1 tag, but left the git version in the `version`, so (as of now) going to https://pytorch.org/docs/1.9.0/index.html and looking at the version in the upper-left corner shows "1.9.0a0+git5f0bbb3" not "1.9.0". This PR should change that to cut off everything after and including the "a".
It should be cherry-picked to the release/1.9 branch so that the next rc will override the current documentation with a "cleaner" version.
brianjo
Pull Request resolved: https://github.com/pytorch/pytorch/pull/58486
Reviewed By: zou3519
Differential Revision: D28640476
Pulled By: malfet
fbshipit-source-id: 9fd1063f4a2bc90fa8c1d12666e8c0de3d324b5c