test: Improve test suite setup

spec/dummy/config/initializers/active_storage.rb

@@ -1,7 +1,9 @@
-ActiveSupport::Reloader.to_prepare do
+Rails.application.reloader.to_prepare do
   ActiveStorage::Attachment.class_eval do
-    def self.ransackable_attributes(auth_object = nil)
-      %w[blob_id created_at id name record_id record_type]
+    class << self
+      def ransackable_attributes(auth_object = nil)
+        %w[blob_id created_at id name record_id record_type]
+      end
     end
   end
 end