CI: Add check for Gitlab/Github remotes in sync

To avoid merging on Gitlab with Github remote out of sync while we are
moving to Github development.

.gitlab-ci.yml

@@ -1,5 +1,6 @@
 stages:
   - build
+  - test
   - deploy
 
 
@@ -80,6 +81,15 @@ build_and_test_qemu:
     - export MQTT_PUBLISH_MSG_len_3=20  MQTT_PUBLISH_MSG_repeat_3=20
     - python Runner.py $TEST_PATH -c $MQTT_PATH/ci/publish_connect_mqtt_qemu.yml -e $TEST_PATH/env.yml
 
+check_remotes_sync:
+  stage: test
+  when: on_success
+  script:
+    - *add_gh_key_remote
+    - git fetch --depth=1 origin master
+    - git fetch --depth=1 github master
+    - test "$(git rev-parse origin/master)" == "$(git rev-parse github/master)"
+
 push_master_to_github:
   stage: deploy
   image: ${CI_DOCKER_REGISTRY}/esp32-ci-env