GHC 9.2 support

[DrewFenwick]

Building under GHC 9.2.1 is currently held up by generics-sop, see well-typed/generics-sop#145

[soenkehahn]

I just created #66 to get a working CI in place. (Reviews appreciated.) After that is merged, and well-typed/generics-sop#145 is fixed, it'd be good to add a stack.yaml file to CI for ghc-9.2. As part of the fix for this issue here, I mean.