Fixes broken monkey patch of #form_with

[alpaca-tc]

In rails 5.1, 5.2 provide #form_with method for view.
Unfortunately, the documented code doesn't work because current ransack's monkey patch is broken.

http://api.rubyonrails.org/v5.2/classes/ActionView/Helpers/FormHelper.html#method-i-form_with
form_with model: Cat.new do |form|
  form.text_field :cats_dont_have_gills
  form.text_field :but_in_forms_they_can
end