Added nvidia drivers

flake.nix

@@ -1,5 +1,13 @@
 {
   description = "Tool to build NixOS for GCP.  ";
+  nixConfig = {
+    extra-substituters = [
+      "https://cuda-maintainers.cachix.org"
+    ];
+    extra-trusted-public-keys = [
+      "cuda-maintainers.cachix.org-1:0dq3bujKpuEPMCX6U4WylrUDZ9JyUG0VpVZa7CNfq5E="
+    ];
+  };
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
     flake-utils.url = "github:numtide/flake-utils";