message: remove libco from submodule
diff: -[submodule "thirdparty/libco"]
  - path = thirdparty/libco
  - url = https://github.com/Tencent/libco.git
  [submodule "thirdparty/hiredis"]
  path = thirdparty/hiredis
  url = https://github.com/redis/hiredis.git
  