As one of the most popular duos in country music (or country-pop crossover), Dan + Shay are known as serious romantics, to the point where they acknowledge and joke about how many marches down the aisle or first dances they’ve provided the soundtrack for. But with their new single, “Say So,” they’re making a temporary switch from wedding songs to a trying-to-prevent-a-funeral song. “Say So,” which comes out Friday as the first single from the duo’s forthcoming album, makes it clear in the first