Allow pull request updates

Author: sergeychernyshev

.github/workflows/gitterra.yml

@@ -11,6 +11,7 @@ permissions:
   contents: read
   pages: write
   id-token: write
+  pull-requests: write
 
 # Allow only one concurrent deployment, skipping runs queued between the run in-progress and latest queued.
 # However, do NOT cancel in-progress runs as we want to allow these production deployments to complete.