Removes close_db_connection! deprecation warning (#334)

Method was deprecated in Rails
rails/rails@a93d8fe

Author: kinduff

CHANGELOG

@@ -1,6 +1,7 @@
 FUTURE
 
 - FIX: Typo in `group_ids_lookup` option name in Redis params exclusion list that was preventing the use of the redis backend along with this option.
+- FIX: Removes close_db_connection! deprecation warning.
 
 28-06-2023
 

lib/message_bus/rack/middleware.rb

@@ -199,7 +199,9 @@ def close_db_connection!
     # ConnectionManagement in Rails puts a BodyProxy around stuff
     #  this means connections are not returned until rack.async is
     #  closed
-    if defined? ActiveRecord::Base.clear_active_connections!
+    if defined? ActiveRecord::Base.connection_handler
+      ActiveRecord::Base.connection_handler.clear_active_connections!
+    elsif defined? ActiveRecord::Base.clear_active_connections!
       ActiveRecord::Base.clear_active_connections!
     end
   end