nixosTests.systemd-networkd: remove wireguard kernel module

config.boot.kernelPackages.wireguard evaluates to null on machine
closure having a > 5.6 Linux kernels, hence making the evaluation of
this test fail.

Wireguard is now part of the mainline Linux kernel, we do not need to
to add it via a additional kernel module anymore for this test.

nixos/tests/systemd-networkd.nix

@@ -6,7 +6,6 @@ let generateNodeConf = { lib, pkgs, config, privk, pubk, peerId, nodeId, ...}: {
       networking.firewall.enable = false;
       virtualisation.vlans = [ 1 ];
       environment.systemPackages = with pkgs; [ wireguard-tools ];
-      boot.extraModulePackages = [ config.boot.kernelPackages.wireguard ];
       systemd.network = {
         enable = true;
         netdevs = {