This is up to you. We only provide YML. if you use an older or newer version. That will depend a lot on your need. Obviously features of a higher version of the Docker-compose would not work on older versions. But it does not influence Dgraph at all.
To know this you need to evaluate all versions of Docker-compose. And see what can be good or bad by adopting an older or newer version.
Anyway, if you need to use an older version. That’s neutral to the Dgraph. But support for older docker-compose yml versions you will only have in the docker community.
Cheers.