DEV: handle add_to_serializer deprecations

plugin.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 # name: discourse-custom-wizard
 # about: Forms for Discourse. Better onboarding, structured posting, data enrichment, automated actions and much more.
-# version: 2.6.10
+# version: 2.6.11
 # authors: Angus McLeod, Faizaan Gagan, Robert Barrow, Keegan George, Kaitlin Maddever, Juan Marcos Gutierrez Ramos
 # url: https://github.com/paviliondev/discourse-custom-wizard
 # contact_emails: development@pavilion.tech
@@ -185,17 +185,17 @@ after_initialize do
     end
   end
 
-  add_to_serializer(:site, :include_wizard_required?) do
+  add_to_class(:site_serializer, :include_wizard_required?) do
     scope.is_admin? && Wizard.new(scope.user).requires_completion?
   end
 
-  add_to_serializer(:site, :complete_custom_wizard) do
+  add_to_class(:site_serializer, :complete_custom_wizard) do
     if scope.user && requires_completion = CustomWizard::Wizard.prompt_completion(scope.user)
       requires_completion.map { |w| { name: w[:name], url: "/w/#{w[:id]}" } }
     end
   end
 
-  add_to_serializer(:site, :include_complete_custom_wizard?) do
+  add_to_class(:site_serializer, :include_complete_custom_wizard?) do
     complete_custom_wizard.present?
   end