pkgsStatic.haskellPackages.ghc: 9.4 -> 9.12

We recently merged changes to build TemplateHaskell with iserv-proxy,
which allows us to bump pkgsStatic from GHC 9.4 to GHC 9.8+. Currently,
GHC 9.10 is the default, but it fails some builds with TH (for example
`pkgsStatic.haskell.packages.native-bignum.ghc910.jose`), which succeed
with GHC 9.12.

Resolves #275304

pkgs/top-level/all-packages.nix

@@ -4778,10 +4778,9 @@ with pkgs;
 
   haskellPackages = recurseIntoAttrs (
     # Prefer native-bignum to avoid linking issues with gmp;
-    # TemplateHaskell doesn't work with hadrian built GHCs yet
-    # https://github.com/NixOS/nixpkgs/issues/275304
+    # GHC 9.10 doesn't work too well with iserv-proxy.
     if stdenv.hostPlatform.isStatic then
-      haskell.packages.native-bignum.ghc94
+      haskell.packages.native-bignum.ghc912
     # JS backend can't use gmp
     else if stdenv.hostPlatform.isGhcjs then
       haskell.packages.native-bignum.ghc910

pkgs/top-level/release-haskell.nix

@@ -428,15 +428,6 @@ let
                 postgrest
                 ;
             };
-
-            haskell.packages.native-bignum.ghc9103 = {
-              inherit (packagePlatforms pkgs.pkgsStatic.haskell.packages.native-bignum.ghc9103)
-                hello
-                random
-                QuickCheck
-                terminfo # isn't bundled for cross
-                ;
-            };
           };
 
       pkgsCross = {