[llvm] github-upload-release.py: Fix bug preventing release creation (PR #84571)

[Aiden Grossman via llvm-commits]

https://github.com/boomanaiden154 approved this pull request.

LGTM. Wish I would've caught this in the original patch that changed this. Probably again highlights the need for better testing when someone has time to get that done.

https://github.com/llvm/llvm-project/pull/84571