title: Github webhook for Pull Request Events Will not trigger Gitlab Pipeline
body: <p>I am trying to trigger a GitLab pipeline from an action on a GitHub pull request. I have configured a webhook in GitHub to send to GitLab to trigger the GitLab pipeline. However, when the webhook fires, GitLab returns a 400 response. This appears to be because the GitHub webhook payload does not have a <code>REF</code> field.</p>
  <p>Does anyone know how to trigger a GitLab Pipeline from a Pull Request event in GitHub?</p>