Create a non-root user in the ENTRYPOINT

[ucan-lab]

#264

If you add a user in the Dockerfile, the user will be generated with the uid and gid of the host user at the time of the Docker build.
This means that it will only work in the environment where it was built with Docker.
(Automatic mapping for Docker for Mac)

If you create a non-root user in ENTRYPOINT, the user will be added when the container is created.
This allows it to run even in environments where Docker is not built, improving portability.