Freeze mutable constant in pipeline presenter

ee/app/models/ee/ci/pipeline.rb

 module EE
   module Ci
     module Pipeline
-
       EE_FAILURE_REASONS = {
         activity_limit_exceeded: 20,
         size_limit_exceeded: 21

ee/app/presenters/ee/ci/pipeline_presenter.rb

@@ -4,7 +4,7 @@ module EE
       EE_FAILURE_REASONS = {
         activity_limit_exceeded: 'Pipeline activity limit exceeded!',
         size_limit_exceeded: 'Pipeline size limit exceeded!'
-      }
+      }.freeze
     end
   end
 end