NEW HOLLYWOOD ‘DOS ‘Tis the season to take glam hair cues from iconic silver screen stars. At the Met Gala, Yara Shahidi’s loose curls channeled Josephine Baker, while Billie Eilish’s volumized bob nodded to Marilyn Monroe. The retro waves on Eiza González at the Met Gala and Amanda Seyfried’s Oscar updo — both created by…