add brakeman beta channel (qltysh#1073)

* add brakeman beta channel

* Brakeman beta will point to version 5.3.1

* Update config/engines.yml

reference the channel name and not the specific image tag generated by the build

Co-authored-by: Federico Moyá  <[email protected]>

Co-authored-by: Federico Moyá  <[email protected]>

Author: RubyBrewsday

config/engines.yml

@@ -18,6 +18,7 @@ black:
 brakeman:
   channels:
     stable: codeclimate/codeclimate-brakeman
+    beta: codeclimate/codeclimate-brakeman:beta
   description: A static analysis tool which checks Ruby on Rails applications for security vulnerabilities.
 bundler-audit:
   channels: