For the past year, if not longer, Carey Mulligan has been rumored to be playing the female lead in Bradley Cooper's Leonard Bernstein biopic Maestro, and now Deadline reports that her casting has been made official -- which is both exciting and a tiny bit discouraging. See, Mulligan will be playing the legendary composer's wife, Felicia Montealegre Cohn Bernstein, who was born in Costa Rica and grew up in Chile. Her mother was Costa Rican, and her father was American, as well as Jewish. Mulligan certainly looks like Felicia, but she's English, so I'm not sure I'…