object_resolver need to pass the *a, or some cases will cause exception

Signed-off-by: Alexander Artemenko <svetlyak.40wt@gmail.com>

pingback/__init__.py

@@ -99,7 +99,7 @@ def ping_func(source, target):
             raise PingbackError(PingbackError.TARGET_IS_NOT_PINGABLE)
 
         object_resolver = kwargs[name]
-        obj = object_resolver(**kw)
+        obj = object_resolver(*a, **kw)
 
         content_type = ContentType.objects.get_for_model(obj)
         try: