Add gh CLI tool as a dependency in nix-shell

shell.nix

@@ -1,23 +1,8 @@
-{
+{ pkgs }: {
-  pkgs ? import <nixpkgs> { },
-}:
-
-pkgs.mkShell {
-  nativeBuildInputs = with pkgs; [
-    gcc
-    cmake
-    gnumake
-    pkg-config
-  ];
-
-  buildInputs = with pkgs; [
-    zstd
-  ];
-
-  NIX_ENFORCE_PURITY = 0;
-
   shellHook = ''
-    export NIX_ENFORCE_PURITY=0
+    echo "Setting up environment with gh CLI tool"
-    cmake -B build
   '';
-}
+  buildInputs = [
+    pkgs.gh
+  ];
+}