Use host yubikey-agent inside a docker container#143

Hi, thanks for the great agent. I've been using it on my Mac without a problem! However recently I need to use the Yubikey-agent inside a docker container because we need to ssh to a remote machine inside the container, but we'd like to have everyone use their own local ssh setup, i.e. yubikey-agent on my Mac. Setting up the environment `SSH_AUTH_SOCK` inside the container to the agent socket on my host machine with proper mounting didn't work. I also saw other ways to mount special path `/run/host-services/ssh-auth.sock` to the container, but it didn't work out either. Do you have any suggestion on how to use this agent inside a docker container? Thanks!