fix python build · Bit-Quill/tinkerpop@3634396

Non-nullable property 'Serializer' must contain a non-null value when exiting constructor. Consider declaring the property as nullable.

Possible null reference argument for parameter 'path' in 'SocketServerSettings SocketServerSettings.FromYaml(string path)'.

Non-nullable field 'Serializer' must contain a non-null value when exiting constructor. Consider declaring the field as nullable.