Add rebase command to prow commands

sync with pipelines-as-code-prow repo

Author: chmouel

Diff for: .tekton/prow.yaml

@@ -4,7 +4,7 @@ metadata:
   name: prow-commands
   annotations:
     pipelinesascode.tekton.dev/pipeline: "https://raw.githubusercontent.com/openshift-pipelines/pipelines-as-code-prow/refs/heads/main/pipeline-prow.yaml"
-    pipelinesascode.tekton.dev/on-comment: "^/(help|merge|lgtm|(assign|unassign|label|unlabel)[ ].*)$"
+    pipelinesascode.tekton.dev/on-comment: "^/(help|rebase|merge|lgtm|(assign|unassign|label|unlabel)[ ].*)$"
     pipelinesascode.tekton.dev/max-keep-runs: "2"
 spec:
   params: