fix: add missing permissions to PR validation workflow (#6)

Signed-off-by: Simon Davies <simongdavies@users.noreply.github.com>

Author: simongdavies

.github/workflows/pr-validation.yml

@@ -6,6 +6,9 @@ on:
   push:
     branches: [main]
 
+permissions:
+  contents: read
+
 env:
   # Consistent image tag for CI
   IMAGE_TAG: ci-${{ github.sha }}