Newly brunette Nantucket native Meghan Trainor has released her first new song since winning the best new artist Grammy a few weeks back. Trainor dropped “No,’’ the first song from her soon-to-be-released second album, “Thank You,’’ and it has a slight Caribbean flavor. Talking about the new record, the 22-year-old singer told EW: “It sounds like the girl version of a Bruno Mars record. It’s kind of a throwback.’’