Is expiation for an oath (kaffarat yamin) obligatory upon a woman who swore not to go to a certain place and then went there?

The jurists stipulated that an oath must be sworn by Allah Almighty or by one of His attributes. If a person swears by one of His attributes with the intention of an oath, then his oath is binding, and if he breaks it, expiation becomes due. The phrase mentioned in the question is not an oath by Allah or by one of His names, and therefore, no expiation is incurred.