reuniting with her “9 to 5” co-stars, Lily Tomlin and Jane Fonda.The country music icon, 75, will star in an upcoming episode of “Grace and Frankie,” Netflix confirmed on Friday.The streaming service didn’t divulge what role Parton will play on the hit sitcom, which has been running since 2015.Production of the seventh and final season of “Grace and Frankie” wrapped earlier this week, meaning the “Jolene” songstress has already filmed her cameo alongside Tomlin, 82, and Fonda, 83.