Update tooling/rubocop/cop/sagittarius/error_code.rb

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Signed-off-by: Dario Pranjic <96529060+Knerio@users.noreply.github.com>

Author: Knerio

tooling/rubocop/cop/sagittarius/error_code.rb

@@ -92,10 +92,6 @@ def filepath(node)
           node.location.expression.source_buffer.name
         end
 
-        def in_mutation?(node)
-          dirname(node).include?('app/mutations') # .include? because the path is ../app/mutations/...
-        end
-
         def in_service?(node)
           dirname(node).include?('app/services') # .include? because the path is ../app/services/...
         end