[llvm] [GitHub][workflows] Ask reviewers to merge PRs when author can not (PR #81142)

[Aiden Grossman via llvm-commits]

https://github.com/boomanaiden154 commented:

No major issues on my end. I'm wondering if at some point we want to split `github-automation.py` given it serves quite a few functions at this point that don't seem to overlap super well. That's a separate discussion/PR though.

https://github.com/llvm/llvm-project/pull/81142