move system packages declaration to modules dir

nixos/configuration.nix

@@ -15,6 +15,7 @@ in
       # Include the results of the hardware scan.
       ./hardware-configuration.nix
       ./packages.nix
+      ./modules/nitrokey.nix
     ];
 
   services.davfs2.enable = true;
@@ -45,16 +46,16 @@ in
   environment.systemPackages = [
     pkgs.sbctl
   ];
-   # Lanzaboote currently replaces the systemd-boot module.
-   # This setting is usually set to true in configuration.nix
-   # generated at installation time. So we force it to false
-   # for now.
-   boot.loader.systemd-boot.enable = lib.mkForce false;
+  # Lanzaboote currently replaces the systemd-boot module.
+  # This setting is usually set to true in configuration.nix
+  # generated at installation time. So we force it to false
+  # for now.
+  boot.loader.systemd-boot.enable = lib.mkForce false;
 
-   boot.lanzaboote = {
-     enable = true;
-     pkiBundle = "/etc/secureboot";
-   };
+  boot.lanzaboote = {
+    enable = true;
+    pkiBundle = "/etc/secureboot";
+  };
 
   # make the boot look good
   boot.plymouth.enable = true;
@@ -143,8 +144,6 @@ in
     package = pkgs.pulseaudioFull;
   };
 
-  # Nitrokey support
-  services.udev.packages = [ pkgs.nitrokey-udev-rules ];
 
   # Enable the X11 windowing system.
   services.xserver.enable = true;