Chris Willman Senior Music Writer and Chief Music Critic Tish Melton, the 17-year-old singer who recently made a splash with her official debut single, “Michelle,” can’t wait to graduate high school next year and devote herself fully to her nascent music career. But in the meantime she’s got a hell of an early graduation present: a forthcoming debut EP helmed by one of the music world’s most notable artist-producers, Brandi Carlile.