American Idol wrapped up its 20th season on Sunday (May 22). The three finalists included HunterGirl, Leah Marlene, and Noah Thompson. Judge Katy Perry joined Leah Marlene for a duet on “Firework.” Judge Luke Bryan and HunterGirl sang “I Told You So.” Noah Thompson and Melissa Etheridge collaborated on “I’m Not The Only One.” The three-hour episode featured performances from Luke Bryan, Thomas…