We’re still working on this. This is the most recent update:
"It’s a priority for us to be able to support Mojave in the near term. It will require a significant upgrade to our virtualization infrastructure to be able to run it: Mojave isn’t supported on the VMware version we are already running.
We’re working to make that happen in the next couple of weeks, after which we will be in a position to try to build new images that run Mojave."