fix: skip polymorphic associations in active_storage check

Author: matthv

app/services/forest_liana/resources_getter.rb

@@ -411,6 +411,7 @@ def get_one_association(name)
 
     def is_active_storage_association?(association)
       return false unless association
+      return false if SchemaUtils.polymorphic?(association)
 
       klass_name = association.klass.name
       klass_name == 'ActiveStorage::Attachment' ||