ci: set proper permission for spam detection action

The default permission of Neuron repo is read-only so the
permission write should be specify explicitly

.github/workflows/spam-comment-detection.yaml

@@ -4,6 +4,9 @@ on:
   issue_comment:
     types: [created, edited]
 
+permissions:
+  issues: write
+
 jobs:
   detect-spam:
     runs-on: ubuntu-latest