Support GHC2024

GHC 9.10 will support a new language edition `GHC2024` (https://gitlab.haskell.org/ghc/ghc/-/merge_requests/12084). I realised today that this will require updates in Cabal too.

(Side note: for language extensions, GHC has a test to make sure that all extensions get added to Cabal. Should we do the same for language editions?)