Update GitHub Actions workflow to use actions/checkout@v6 for improve…

…d functionality and compatibility.

Update GitHub Actions workflow to use latest action versions for Dock…

…er build and publish process, enhancing compatibility and performance.

Fix MOTD formatting in entrypoint script. Ref #11

Add health check to Dockerfile for SSH daemon

This update introduces a HEALTHCHECK instruction to the Dockerfile, ensuring that the SSH daemon is running properly. The health check runs every 30 seconds and verifies the process is active, enhancing the reliability of the Docker image.

Do not change ownership of host keys directory (#10)

This line was preventing me from mounting my own persistent host keys.
I also don't think it should be owned by the unprivileged tunnel user.

Update Dockerfile to remove default SSH host keys and ensure secure S…

…SH setup

Enable MOTD and last login display in SSHD configuration

Enable MOTD and last login display in SSHD configuration

Fix duplicate tag issues

Fixed build order