haskellPackages.nix-serve-ng: build against lix

Upstream nix-serve-ng has switched to Lix as its supported Nix
implementation, so follow upstream and build the Lix-backed variant
by default. Add a release-notes entry since this changes pkgs.nix-serve-ng.

doc/release-notes/rl-2611.section.md

@@ -25,6 +25,8 @@
 
 - `uhttpmock` providing 0.0 ABI was removed. `uhttpmock_1_0` providing 1.0 ABI was renamed to `uhttpmock` and `uhttpmock_1_0` was kept as an alias.
 
+- `nix-serve-ng` (and `haskellPackages.nix-serve-ng`) is now built against Lix instead of CppNix, following upstream which has switched to Lix as its supported Nix implementation.
+
 - Linux kernel configuration has been moved out of the `linux-kernel` field of the platform structure into the kernel builders:
   - `linux-kernel.name` has been removed.
   - `linux-kernel.target` is available as the `target` parameter and passthru attribute on the kernel builders.

pkgs/development/haskell-modules/configuration-nix.nix

@@ -529,7 +529,9 @@ builtins.intersectAttrs super {
   # Add necessary reference to gtk3 package
   gi-dbusmenugtk3 = addPkgconfigDepend pkgs.gtk3 super.gi-dbusmenugtk3;
 
-  nix-serve-ng = lib.pipe (super.nix-serve-ng.override { nix = pkgs.nixVersions.nix_2_28; }) [
+  # Upstream has switched to Lix as its supported Nix implementation.
+  nix-serve-ng = lib.pipe (super.nix-serve-ng.override { nix = pkgs.lix; }) [
+    (enableCabalFlag "lix")
     # nix-serve-ng isn't regularly released to Hackage
     (overrideSrc {
       src = pkgs.fetchFromGitHub {