[user module] actually call the module

and fix some issues

machines/modules/malobeo/users.nix

@@ -1,7 +1,7 @@
-{config, lib, pkgs, ...}:
+{config, lib, pkgs, inputs, ...}:
 let 
   cfg = config.malobeo.users;
-  sshKeys = import ../ssh_keys.nix;
+  sshKeys = import ( inputs.self + /machines/ssh_keys.nix);
 in
 {
   options.malobeo.users = {
@@ -21,7 +21,7 @@ in
       environment.systemPackages = with pkgs; [];
     })
     (lib.mkIf cfg.admin {
-      users.user.admin = {
+      users.users.admin = {
         isNormalUser = true;
         description = "admin user, passwordless sudo access, only ssh";
         hashedPassword = null;