Update to msgpack 1.0

In %Turris OS 5.0, sentinel-dynfw-client fails with:

2020-04-16 13:47:14,209 - DEBUG - waiting for connection
2020-04-16 13:47:14,212 - DEBUG - connected
2020-04-16 13:47:23,730 - ERROR - Invalid message: Broken message

The issue is in incompatibility with msgpack 1.0:

Major breaking changes in msgpack 1.0

• Unpacker
  • encoding option is removed. You can use raw=True to support old format.