Remove non-working workflow

This workflow fail to start because of missing dependencies:

> Unhandled error: TypeError: Cannot read properties of undefined (reading 'listWorkflowRunArtifacts')

Additionally, on the upstream repo, this workflow is broken:
https://github.com/puppetlabs/puppet-runtime/actions/workflows/comment_on_pr.yaml

There is no point in keeping it.

Fixes: #37

Author: smortex