Automatically import nixos-modules to get the libS input, fix flake check

flake.nix

@@ -9,13 +9,15 @@
     };
   };
 
-  outputs = { nixpkgs-lib, ... }:
+  outputs = { nixos-modules, nixpkgs-lib, ... }:
     let
       inherit (nixpkgs-lib) lib;
       ls = dir: lib.attrNames (builtins.readDir (./. + "/${dir}"));
     in
     {
-      nixosModule = _: {
+      nixosModule = { ... }: {
+        modules = [ nixos-modules.nixosModule ];
+
         imports = (dir: map (file: ./. + "/${dir}/${file}") (ls dir)) "modules";
       };
     };