Fix tax category params

The former ones were not correct, probably just a leftover from
a cut and paste.

admin/app/controllers/solidus_admin/tax_categories_controller.rb

@@ -34,7 +34,7 @@ def load_tax_category
  end
 
  def tax_category_params
- params.require(:tax_category).permit(:tax_category_id, permitted_tax_category_attributes)
+ params.require(:tax_category).permit(:name, :description, :is_default, :tax_code)
  end
  end
 end