DEV: use of as_json without only no longer allowed

See https://meta.discourse.org/t/preventing-accidental-serialization-of-activerecord-models/314495

spec/components/custom_wizard/action_spec.rb

@@ -173,7 +173,7 @@ describe CustomWizard::Action do
     steps = wizard.steps
     wizard.create_updater(steps[0].id, {}).update
     wizard.create_updater(steps[1].id,
-      step_2_field_7: upload.as_json
+      step_2_field_7: upload.as_json(only: [:id, :url, :user_id])
     ).update
     expect(user.profile_background_upload.id).to eq(upload.id)
   end

spec/components/custom_wizard/wizard_spec.rb

@@ -230,7 +230,9 @@ describe CustomWizard::Wizard do
     before do
       enable_subscription("standard")
       @wizard.restart_on_revisit = true
-      CustomWizard::Template.save(@wizard.as_json)
+      CustomWizard::Template.save(
+        CustomWizard::WizardSerializer.new(@wizard, root: false).as_json
+      )
     end
 
     it "returns to step 1 if option to clear submissions on each visit is set" do