[llvm] github-upload-release.py: add requirements and lock files for installing dependencies (PR #169461)

[Aiden Grossman via llvm-commits]

boomanaiden154 wrote:

> I changed it to requirements.txt and a generated lockfile for this PR, however I think it would be good to consider adding the inline script metadata to make it obvious to someone looking at the script what dependencies it needs installed are (and that follows the script if it ever gets moved around in the repository.

You can add a docstring that references the `requirements.txt` file.

https://github.com/llvm/llvm-project/pull/169461