Hilary Duff is back — and older and wiser. The multi-hyphenate has shared her highly-anticipated single “Mature.” On the song, Duff takes a pop-rock jaunt through the past as she sings to a younger version of herself. “She looks like all of your girls but blonder/A little like me, but younger,” Duff offers over a glimmering blend of synths and guitar licks. “‘Mature’ is a little conversation that my present self is having with my younger self,” Duff said in a release. “The two of us are