Remove code path for Rails 5.2 support

lib/factory_bot_rails/factory_validator.rb

@@ -15,25 +15,9 @@ def run
     private
 
     def validate_compiled_factory
-      if Rails.version >= "6.0"
-        rails_6_0_support
-      else
-        rails_5_2_support
-      end
-    end
-
-    def rails_6_0_support
       proc do |event|
         @validators.each { |validator| validator.validate!(event.payload) }
       end
     end
-
-    def rails_5_2_support
-      proc do |*notification_event_arguments|
-        event = ActiveSupport::Notifications::Event.new(*notification_event_arguments)
-
-        rails_6_0_support.call(event)
-      end
-    end
   end
 end