It’s been a while since we watched “Project Runway,’’ and we were tempted to say “auf Wiedersehen’’ altogether after learning that Heidi Klum isn’t involved in the new season. (Temporarily, at least, the Lifetime show has been renamed “Project Runway: Under the Gunn,’’ and the German-American supermodel isn’t participating.) But we might need to tune in again just to watch Newton native Sam Donovan, a 23-year-old Parsons grad who last week wowed the show’s judges, who include designer Rachel Roy, celebrity stylist Jen Rade, and TV fashion correspondent Zanna Roberts Rassi. Donovan’s bio is certainly compelling: “Raised by wealthy, divorced parents in a dysfunctional all-American family, he bounced around all over suburban Boston. He was bullied in middle school before he even knew he was gay, but his mother came to his defense, helping him become the self-assured person he is today.’’ We’re hoping Donovan can, in the words of host Tim Gunn, make it work again on Thursday’s episode.