add github actions permission

Signed-off-by: Peter Siegmund <developer@mars3142.org>

.github/workflows/esp32_build.yaml

@@ -7,6 +7,10 @@ on:
   schedule:
     - cron: "0 5 * * 3"
 
+permissions:
+  contents: read
+  pull-requests: write
+
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}
   cancel-in-progress: true