Veep executive producer Frank Rich says production on the series’ seventh and final season is on hold while star Julia Louis-Dreyfus undergoes treatment for breast cancer. The show was expected to adjust production to accommodate Louis-Dreyfus’ treatment if needed. In an interview Wednesday on SiriusXM, Rich confirmed production has been delayed. “We're obviously postponing production of the show — we were supposed to have started now — while she's in treatment,” Rich…