module nitrokey: drop option group

Since the update of the nitrokey-app to 1.4.2 the group option is no
longer supported.

nixos/modules/hardware/nitrokey.nix

@@ -19,23 +19,9 @@ in
         nitrokey-app package, depending on your device and needs.
       '';
     };
-
-    group = mkOption {
-      type = types.str;
-      default = "nitrokey";
-      example = "wheel";
-      description = ''
-        Grant access to Nitrokey devices to users in this group.
-      '';
-    };
   };
 
   config = mkIf cfg.enable {
-    services.udev.packages = [
-      (pkgs.nitrokey-udev-rules.override (attrs:
-        { inherit (cfg) group; }
-      ))
-    ];
-    users.groups.${cfg.group} = {};
+    services.udev.packages = [ pkgs.nitrokey-udev-rules ];
   };
 }