Mark AR specific tests with AR tag

spec/lib/config_spec.rb

@@ -360,7 +360,7 @@
       expect(Doorkeeper.config.enable_application_owner?).not_to be(true)
     end
 
-    context "when enabled without confirmation" do
+    context "when enabled without confirmation", active_record: true do
       class ApplicationWithOwner < ActiveRecord::Base
         include Doorkeeper::Orm::ActiveRecord::Mixins::Application
       end
@@ -388,7 +388,7 @@ class ApplicationWithOwner < ActiveRecord::Base
       end
     end
 
-    context "when enabled with confirmation set to true" do
+    context "when enabled with confirmation set to true", active_record: true do
       class ApplicationWithOwner < ActiveRecord::Base
         include Doorkeeper::Orm::ActiveRecord::Mixins::Application
       end

spec/models/doorkeeper/application_spec.rb

@@ -518,7 +518,7 @@ def self.generate
     end
   end
 
-  context "when custom model class configured" do
+  context "when custom model class configured", active_record: true do
     class CustomApp < ::ActiveRecord::Base
       include Doorkeeper::Orm::ActiveRecord::Mixins::Application
     end