More than a quarter-century after Uncle Tupelo released the genre-defining No Depression, does the term "alt-country" still mean anything? If Brothers Osborne are to be believed, the current stagnation of Florida Georgia Line-derived mainstream country means it's about time for the phrase to be resurrected. "I've always compared to the early '90s when hair metal was so huge, and you had these bands like Warrant, who were more about showing off and about the picture than they were about the music," singer T.J. Osborne told Rolling Stone early last year. "It got to a point where it became so huge…