Add bundle audit to CI (#263)

* Add bundle-audit gem

* Update vulnerable brakeman gem

* Fix "Insecure Source URI found" issue for Rails

.circleci/config.yml

@@ -33,6 +33,10 @@ jobs:
           name: Bundle Install
           command: bundle check || bundle install
 
+      - run:
+          name: Bundle audit
+          command: bundle exec bundle audit update && bundle exec bundle audit check -v
+
       - run:
           name: Rubocop
           command: bundle exec rubocop