Merge branch 'bundle-audit-ignore-redcloth' into 'master'

Remove allowed to fail by ignoring RedCloth

Having `Allowed to fail` jobs will only make sure we'll miss something
when it should fail, so I excluded a known issue which has been an
issue a long time now.

Now when this build is not green we know we should look at it and pay
attention.

See merge request !3215

.gitlab-ci.yml

@@ -150,11 +150,10 @@ bundler:audit:
   stage: test
   script:
     - "bundle exec bundle-audit update"
-    - "bundle exec bundle-audit check"
+    - "bundle exec bundle-audit check --ignore OSVDB-115941"
   tags:
     - ruby
     - mysql
-  allow_failure: true
 
 # Ruby 2.2 jobs