Recently, Bostonian embrace popped painted pianos across the city and neighboring Cambridge. Celebrity Series of Boston placed 60 upright pianos decorated by local artists late last week. Each instrument bears a simple message: “Play Me, I’m Yours.” And play residents and visitors have. At historic Faneuil Hall’s Quincy Market food hall on Tuesday, a group of high school students from Boston took turns singing and playing Adele’s “Hello” and other pop tunes while…