test only: fix uniqueness warning

This test on mysql rails 6.0 was throwing the following warning:

DEPRECATION WARNING: Uniqueness validator will no longer enforce case sensitive comparison in Rails 6.1

test/concerns/hooks_test.rb

@@ -39,7 +39,7 @@ def test_update_descendants_with_changed_parent_value
       model.class_eval do
         before_save :update_name_path
         # this example will only work if the name field is unique across all levels
-        validates :name, :uniqueness => true
+        validates :name, :uniqueness => {case_sensitive: false}
 
         def update_name_path
           self.name_path = [parent&.name_path, name].compact.join('/')