formal-this-repo: post results to the PR

Fix local formality check permissions that are needed to post optional
summaries back to the PR.

Fixes: 1079ad9 ("formal: post summary to the PR")
Signed-off-by: George Sapkin <george@sapk.in>

Author: GeorgeSapkin

.github/workflows/formal-this-repo.yaml

@@ -5,8 +5,11 @@ on:
 
 permissions:
   contents: read
+  pull-requests: write
 
 jobs:
   build:
     name: Test Formalities
     uses: openwrt/actions-shared-workflows/.github/workflows/formal.yml@main
+    with:
+      post_comment: true