no RtuFramer for serial synchronus server

[Loris1123]

It seems like you cannot use an RtuFramer for a synchronus serial server.

pymodbus.server.async.StartSerialServer(context, identity=None,
    framer=ModbusAsciiFramer, **kwargs):

uses a framer as parameter, ModbusAscii as default.

pymodbus.server.sync.StartSerialServer(context=None, identity=None, **kwargs):
    framer = ModbusAsciiFramer

This one uses only the AsciiFramer. No possibility to use RtuFramer