Switch to using Podman to run the service

[cooper667]

Currently we use a very basic docker-compose file to run the service on the VM, but this occasionally doesn't restart correctly (we should ALSO work out why it's failing) and isn't really the correct way to run a persistent container on CoreOS.

A better approach would be using Podman in conjunction with SystemD, similar to the way described here:

https://www.tutorialworks.com/podman-systemd/

(that doesn't factor in how we update the container, ours are tagged with the commit hash.)

We could do something like, write the latest hash to a file somewhere and just have the SystemD or podman config read the tag from there? Then a deploy is:

• Write new tag to that file
• Restart the service