Add a bundle check step to ensure dependencies are correct

This should help prevent merge issues in the future, which caused !6814
to be needed.

.gitlab-ci.yml

@@ -263,6 +263,7 @@ bundler:audit:
   only:
     - master
   script:
+    - bundle check
     - "bundle exec bundle-audit check --update --ignore OSVDB-115941"
 
 migration paths: