Today we updated our Xcode 9.0 beta 5 image to Xcode 9.0 beta 6 (build version
9M214v) with the latest simulators.
You can use this image by specifying Xcode 9.0 in your
machine: xcode: version: "9.0"
This image tag will be automatically upgraded when new betas are released by Apple, until the final release of Xcode 9.