MultiTenant.without does not work for a polymorphic relationship

In the following code.

👍 the `Visit.find_by` query does not add account_id where condition, which is perfect
👎 but, during `visit.save!`, Rails does a `Product` lookup, to which an account_id where condition is added

```ruby
MultiTenant.without do
visit = Visit.find_by(visitable_type: "Product", visitable_id: 1)
visit.last_visit_at = Time.current
visit.save!
end

class Visit < ApplicationRecord
multi_tenant :account
belongs_to :visitable, polymorphic: true
end

class Product < ApplicationRecord
multi_tenant :account
end
```