Simplify strategy to insert records in tests

Since Rails 7.0, the `insert` method automatically generates timestamps.

spec/factory_bot/strategy/insert.rb

@@ -11,11 +11,7 @@ module FactoryBot
         build_class = evaluation.instance_variable_get(:@attribute_assigner)
                                 .instance_variable_get(:@build_class)
 
-        timestamps = { created_at: Time.current, updated_at: Time.current }.select do |attribute, _|
+        build_class.insert!(@strategy.result(evaluation))
-          build_class.has_attribute?(attribute)
-        end
-
-        build_class.insert!(timestamps.merge(@strategy.result(evaluation)))
       end
     end