remove F() expression

mcserver/views.py

@@ -1510,8 +1510,8 @@ def dequeue(self, request):
             trial.status = "processing"
             trial.server = ip
             trial.hostname = hostname
+            trial.processed_count += 1
             trial.save()
-            trial.objects.update(processed_count=(F("processed_count") + 1))
 
             print(ip)
             print(trial.session.server)