chore: update issue types in bot validation workflow

- Change issue types from 'opened, edited, labeled' to 'labeled'

Author: MarkusNeusinger

.github/workflows/bot-validate-request.yml

@@ -9,7 +9,7 @@ on:
         required: true
         type: string
   issues:
-    types: [opened, edited, labeled]
+    types: [labeled]
 
 concurrency:
   group: validate-plot-request-${{ github.event.issue.number || github.run_id }}