Build config did not create any jobs


my travis build is no longer triggered anymore. My travis file is here:
It shows up under “Requests” in TravisCI with the message: “Build config did not create any jobs” but no build is triggered. The last change i did which might have caused this was reducing the Julia version for building to the latest one only. I can’t see why this should cause the above error.
Can anybody help me finding the cause?

Thanks in advance!