PR Labeler Broken

I noticed that we have a labeler config (https://github.com/apache/beam/blob/master/.github/autolabeler.yml) that used to be working, but no longer is. It would be nice to have PR labels so that we can quickly answer questions like: what are all of the Go PRs that have been completed recently. This is extra nice for new contributors who are trying to find their way around the repo/recent changes.

I suspect that the labeler stopped working because probot support was deprecated in favor of the GitHub Actions labeler.