HLS is broken on GHC 9.12.2

[dhess]

Thanks for the GHC 9.12.2 support!

Unfortunately, HLS needs a workaround for it:

tools = {
  haskell-language-server = {
    src = pkgs.haskell-nix.sources."hls-2.10";
    cabalProjectLocal = ''
      allow-newer: haddock-library:base
    '';
  };
}

Otherwise, haddock-library breaks ghcide because haddock-library 1.11.0 depends on base <4.21.

(This doesn't appear to be specific to haskell.nix and honestly I'm not sure how anyone is using HLS on GHC 9.12.2 — without a similar workaround, anyway — due to this issue.)