host: Fix libvirt's iptables conumdrum

hosts/miku.nix

@@ -5,6 +5,7 @@ let
 in mkHost config {
   userName = "alexander";
   hostName = "miku";
+  primaryInterface = "enp6s0";
   overlays = [ "nur" "unstable" "simple" "custom" "emacs" ];
   hardwareImports = [ "amdgpu" "amd" ];
   programImports = [