Update prt_labels.yml

.github/workflows/prt_labels.yml

@@ -4,12 +4,13 @@ name: Robottelo - CI
 on:
   push:
   pull_request:
-    types: ["opened", "synchronize"]
+    types: ["synchronize"]
 
 jobs:
     prt_labels:
       name: remove the PRT label, if it is a new commit
       runs-on: ubuntu-latest
+      if: contains(github.event.pull_request.labels.*.name, 'PRT')
       steps:
         - name: get the PRT status, it will be empty in case of the new commit
           id: prt