Mergify configuration is invalid on 2.8.x branch

[SethTisue]

I'm seeing this in every PR; an example is #50

@mkurz is there a standard playframework/* Mergify configuration I can pull in from somewhere that doesn't have this problem?

btw this repo is of concern to me because it's one of our sample repos for https://developer.lightbend.com/docs/fortify/current

[mkurz]

Fixed by #54
Just two days ago I opened a PR so we can put a master mergify config in our orgs .github repo: Mergifyio/mergify#4050
Let's see how this works out.