Back in August, Taylor Swift joined her then-boyfriend — now-fiancé — Travis Kelce on his New Heights podcast to announce her 12th studio album, “The Life of a Showgirl.” The record hit streaming services and store shelves on Friday. While not a particularly innovative or poetic work in the singer’s catalogue, “The Life of a Showgirl” is an improvement on her recent pop sound. And Swift’s music is danceable again.