tools: add ability to grab git tag (#77279)
Adds the ability to grab the git tag when using
`generate_torch_version.py` so that users who build from source on a
specific tag will get the version that they expect.
Behavior is now this:
1. Check if git tag is available on current commit
2. If tag available use tagged version, do not attempt to grab other versions
3. If tag is not available, use previous workflow for determining version
Signed-off-by: Eli Uriegas <eliuriegas@fb.com>
Fixes https://github.com/pytorch/pytorch/issues/77052
Pull Request resolved: https://github.com/pytorch/pytorch/pull/77279
Approved by: https://github.com/ezyang
