Docker compose workflow doesn't work as expected

[mehaase]

The docker-compose.yml workflow runs against the :latest tag for the docker image, and the workflow does not depend on the execution of the docker.yml workflow. So it's really testing some previous version of the docker image, not the one associated with the current PR/commit.

We probably need to merge the docker-compose test into the docker workflow in such a way that it runs after the image is successfully built. (And be sure to use the correct tag -- I'm not sure if our docker build updates the :latest tag or not.)