treewide: machine -> nodes.machine

nixos/tests/containers-names.nix

@@ -4,7 +4,7 @@ import ./make-test-python.nix ({ pkgs, lib, ... }: {
     maintainers = with lib.maintainers; [ patryk27 ];
   };
 
-  machine = { ... }: {
+  nodes.machine = { ... }: {
     # We're using the newest kernel, so that we can test containers with long names.
     # Please see https://github.com/NixOS/nixpkgs/issues/38509 for details.
     boot.kernelPackages = pkgs.linuxPackages_latest;