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

[Ryan Mast via llvm-commits]

nightlark wrote:

> This is not how we manage dependencies. This needs to go in a `requirements.txt` along with a generated lockfile, or piggy back off something else.

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.

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