Fastify listening interfaces should be configurable

[rogama25]

I'm currently deploying a labeler inside a Docker container, and this library does not set the internal fastify instance to listen on all interfaces, so I had to set it up like this:
labelerServer.app.listen({port, host: "::"}, callback)

It feels quite wrong having to access the internal fastify object instead of passing it just the same as the port

[futurGH]

This is fixed in 29794f5, just need to publish a release!