Support new GHCs on CI

[tomjaguarpaw]

You'll probably want to cherry-pick this: https://github.com/kowainik/summoner/commit/4e8af8b9b222f65de88b30d688930bd9d2faac37

You can do it like this:

git fetch git@github.com:tomjaguarpaw/summoner.git 9.10
git cherry-pick 4e8af8b9b222f65de88b30d688930bd9d2faac37