Fix kitdiff PR comment (#207)

No idea why this works without the permission on the egui repo 🤔

Author: lucasmerlin

.github/workflows/kitdiff_comment.yml

@@ -3,6 +3,9 @@ on:
   pull_request_target:
     types: [ opened ]
 
+permissions:
+  pull-requests: write
+
 jobs:
   build:
     runs-on: ubuntu-latest