HARRISBURG, Pa. — The candidate had just chided the media minutes earlier for not being tougher on his opponent when the moderator asked him what might be his least favorite campaign question: Why won’t you release your tax returns? It wasn’t a scene from the 2016 presidential race. Rather, it was from this year’s campaign for governor in Pennsylvania, where the Republican challenger who has made millions from his trash-hauling business has refused to release his tax returns. “How much I make or don’t make is nobody’s business, frankly,” the candidate, Scott Wagner, responded during a question-and-answer forum. The incumbent, Democratic Gov.