Update backport.yml

Author: jonathanlukas

.github/workflows/backport.yml

@@ -4,7 +4,9 @@ on:
     types: [closed]
   issue_comment:
     types: [created]
-
+permissions:
+  contents: write # so it can comment
+  pull-requests: write # so it can create pull requests
 jobs:
   backport:
     name: Create backport PRs