CMT announced the second slate of performers for its two-hour TV special, CMT Celebrates Our Heroes: An Artists of the Year Special, on June 3 at 7 p.m. CT. Brandi Carlile, Carrie Underwood, Darius Rucker, Kane Brown, Kristen Bell, Lauren Daigle, Luke Combs, Sam Hunt and Tim McGraw will join previously announce performers Brothers Osborne,…