fix auth diagnostic

Author: thomas loubrieu

.github/workflows/sync_labels.yml

@@ -34,6 +34,8 @@ jobs:
             echo "✅ GH_TOKEN is set"
             echo "Token length: ${#GH_TOKEN}"
           fi
+        env:
+          GH_TOKEN: ${{ secrets.PROJECTS_TOKEN }}
 
       - name: Fetch labels from source repository
         run: |