Build with GHC 9.6

[mightybyte]

Import changes to build with GHC 9.6. This patch serves my purposes for now, but if you need to do things differently to preserve backwards compatibility, feel free to adapt as necessary.

[LaurentRDC]

Thank you for making the the code changes.

There are still some changes required on the packaging side in order for the beam repository to be buildable with GHC 9.6, for example:

• Bumping the upper bound on ghc-prim from <0.10 to <0.11;
• Bumping the upper bound on fgl from <5.8 to <5.9;

Outside of the beam repository, the following is required:

• A new release of pqueue which supports base-4.18 (New release/hackage revision for GHC 9.6.1? lspitzner/pqueue#121);
• A new release of hint supporting GHC 9.6 (Add support for GHC 9.6.1 haskell-hint/hint#158)

For example, to build and test beam-core from this pull request, one must do:

cabal test beam-core --allow-newer=ghc-prim,mtl,pqueue:base,unix,hint:ghc,fgl

[kmicklas]

Can you rebase this? I will merge if it passes CI for the current GHC versions. (Working on updating CI to all the newer GHCs soon.)

[kmicklas]

This isn't complete, but it gets us closer and I verified it doesn't break older versions.