message: ci: add "PR action: cleanup" to the bot's forbiddenLabels list
  PR Close
diff: @@ -32,6 +32,7 @@ merge:
  # list of labels that a PR shouldn't have, checked after the required labels with a regexp
  forbiddenLabels:
  - "PR target: TBD"
  + - "PR action: cleanup"
  - "cla: no"
  # list of PR statuses that need to be successful
  