Add 9.8 builds

I can already compile Ormolu Live without head.hackage using relaxed bounds and an s-r-p for aeson. So I think it already might make sense now, but can of course hold off until 9.8.1 gets released.

mentioned in commit 004a486b

merged

lgtm, no need to wait for 9.8.1, thanks for adding this!

mentioned in merge request !54 (merged)