Summary:
Should fix the following [error](https://github.com/pytorch/pytorch/runs/5058514346#step:13:88):
```
+ git --git-dir /pytorch/pytorch/.git describe --tags --match 'v[0-9]*.[0-9]*.[0-9]*' --exact
fatal: not a git repository: '/pytorch/pytorch/.git'
```
By setting `workdir` correctly for GHA linux and Windows builds

Also, abort `tagged_version` if GIT_DIR does not exist (as this script should only be executed in context of git folder.

Pull Request resolved: https://github.com/pytorch/pytorch/pull/72628

Reviewed By: atalman

Differential Revision: D34120721

Pulled By: malfet

fbshipit-source-id: 035e93e243e601f9c24659cd247f9c029210fba5
(cherry picked from commit 3a6c97b6ddb185d706494f64423a761fee8fce09)
(cherry picked from commit b6df02bbbb5b786b198938ffb5d90fa5251df3eb)