remove unused var

mesads/app/views.py

@@ -478,7 +478,7 @@ def form_valid(self, form):
             try:
                 with transaction.atomic():
                     self.ads_users_formset.save()
-            except IntegrityError as exc:
+            except IntegrityError:
                 errmsg = [
                     c
                     for c in ADSUser._meta.constraints