nixos/testing/network.nix: Add network config to specialisations

nixos/lib/testing/network.nix

@@ -112,6 +112,6 @@ let
 in
 {
   config = {
-    defaults = { imports = [ networkModule nodeNumberModule ]; };
+    extraBaseModules = { imports = [ networkModule nodeNumberModule ]; };
   };
 }

nixos/lib/testing/nodes.nix

@@ -22,6 +22,7 @@ let
               # when the test framework is used by Nixpkgs NixOS tests.
               nixpkgs.config.allowAliases = false;
             })
+          testModuleArgs.config.extraBaseModules
         ] ++ optional config.minimal ../../modules/testing/minimal-kernel.nix;
     };