Update nixpkgs

[deemp]

With current nixpkgs:

• GHC with js-backend doesn't build.
  Build failure: pkgsCross.ghcjs.buildPackages.haskell.compiler.ghc{98,HEAD} NixOS/nixpkgs#286397
  llvm: don't depend on binutils for ghcjs platform NixOS/nixpkgs#302552
  This PR isn't in master yet (https://nixpk.gs/pr-tracker.html?pr=302552).
  Currently not updating to a nixpkgs/staging-next commit because of multiple cache misses.
• There's no GHC 9.8.5
  The PR that adds GHC 9.8.5 was merged very recently haskell.compiler.ghc965: init at 9.6.5 NixOS/nixpkgs#304524
  Currently not updating to a nixpkgs/master commit because of multiple cache misses.