MONGOID-3946 fix the range condition uniqueness validation test (#4701)
MONGOID-3946 fix the range condition uniqueness validation test (#4701)

As documented in https://apidock.com/rails/ActiveRecord/Validations/ClassMethods/validates_uniqueness_of,
:scope option takes one or more columns - it does not take a
Criteria object (i.e. a scope object, confusingly).
The option that takes Criteria/scope object is :conditions.

Change the test to use the correct option.
mongodb/mongoid,mongodb/mongoid,mongodb/mongoid