waitBuildkitRunning may not work properly

[tonzgao]

first time i ran sanic build it resulted in hang. not sure if this is replicable

i can look into this for hacktoberfest laster

[tonzgao]

seems like the docker command checking for status hangs when it succeeds

docker exec -i sanic-buildkitd buildctl --addr tcp://127.0.0.1:3165 build

command should be replaced, not sure with what though. if you just do something like build -> help, for example, subsequent calls to sanic build will fail