fix proto_fill_from_dict handling of lists

steam/util/__init__.py

@@ -113,6 +113,9 @@ def proto_fill_from_dict(message, data, clear=True):
                         ))
 
                 proto_fill_from_dict(getattr(message, key), val)
+        else:
+            if isinstance(val, list):
+                getattr(message, key).extend(val)
             else:
                 setattr(message, key, val)