Start docker composition during integration tests too
Start docker composition during integration tests too

This already existed in the "build and publish" workflow, but not
here. However, we've seen a bunch of tests fail over time with errors
seemingly due to Postgres not having come up by the time tests
start. Let's try putting this here too and see if that fixes it.

mozilla-services/kinto-dist,Kinto/kinto-dist,mozilla-services/kinto-dist,Kinto/kinto-dist