CNN was forced to apologize to Dolly Parton’s family for mistakenly using a photo of a Las Vegas impersonator of the country music legend while reporting on her death. The cable news network aired an image of tribute artist Kelly Vohnn as it covered Parton’s Tuesday death from cancer — leaving the 58-year-old Vohnn stunned as friends began bombarding her with messages. The errant image were broadcast during “Laura Coates Live” some 12 hours after Parton’s death was announced by her family. “We regret the error and apologize to the Parton family,” CNN told The Post in a brief Thursday...