fix(pkgs/nethermind): Use specific version of Nixpkgs to build Nethermind

As newer version of Nixpkgs fail to build it, for example:
https://github.com/metacraft-labs/ethereum.nix/actions/runs/11453835003/job/31867023628

Author: PetarKirov

flake.nix

@@ -11,6 +11,7 @@
     nixpkgs.url = "github:nixos/nixpkgs/24.05";
     nixpkgs-2311.url = "github:nixos/nixpkgs/23.11";
     nixpkgs-unstable.url = "github:nixos/nixpkgs/nixpkgs-unstable";
+    nixpkgs-nethermind.url = "github:nixos/nixpkgs?rev=9c513fc6fb75142f6aec6b7545cb8af2236b80f5";
 
     foundry-nix = {
       url = "github:shazow/foundry.nix/monthly";
@@ -105,6 +106,10 @@
             inherit system;
             nixpkgs = inputs.nixpkgs-2311;
           };
+          pkgsNethermind = lib.extras.nix.mkNixpkgs {
+            inherit system;
+            nixpkgs = inputs.nixpkgs-nethermind;
+          };
         };
 
         # devshell

pkgs/default.nix

@@ -18,13 +18,15 @@
     pkgs,
     pkgsUnstable,
     pkgs2311,
+    pkgsNethermind,
     system,
     ...
   }: let
     inherit (pkgs) callPackage;
     inherit (lib.extras.flakes) platformPkgs platformApps;
     callPackageUnstable = pkgsUnstable.callPackage;
     callPackage2311 = pkgs2311.callPackage;
+    callPackageNethermind = pkgsNethermind.callPackage;
 
     rustToolchain = inputs'.fenix.packages.minimal.toolchain;
 
@@ -67,7 +69,7 @@
       mev-boost-builder = callPackage ./mev-boost-builder {inherit blst;};
       mev-boost-relay = callPackage ./mev-boost-relay {inherit blst;};
       mev-rs = callPackage ./mev-rs {};
-      nethermind = callPackageUnstable ./nethermind {};
+      nethermind = callPackageNethermind ./nethermind {};
       nimbus = callPackageUnstable ./nimbus {};
       nimbus-eth2 = callPackageUnstable ./nimbus-eth2 {
         # For now the nimbus team prefers nim 1.6 over 2.0.