Setting DISCOURSE_MAXMIND_LICENSE_KEY breaks docker image/container build

I have been having the same issue for a while now and had to disable the MaxMind integration in order to rebuild.

I think the issue may have been fixed at least on tests-passed, but I’m on latest stable (3.2.2) so I assumed I would have to wait. However, there is a report of the same with 3.3.0, so perhaps this needs a closer look.