Trace Adkins will co-star in the upcoming film, Bennett’s War, which hits theaters nationwide on Aug. 30. During the flick’s L.A. premiere on Aug. 13, Trace walked the red carpet with his co-stars—Michael Roark, Ali Afshar, Allison Paige and more—as well as his longtime friend Blake Shelton, who was joined by girlfriend Gwen Stefani. For…