nixos/tests/nix-store-veritysetup: fix warnings

        partitions = {

          "nix-store" = {

            storePaths = [ config.system.build.toplevel ];

            stripNixStorePrefix = true;

            nixStorePrefix = "/";

            repartConfig = {

              Type = "linux-generic";

              Label = "nix-store";

        "-f",

        "qcow2",

        "-b",

        "${nodes.machine.system.build.image}/${nodes.machine.image.repart.imageFile}",

        "${nodes.machine.system.build.image}/${nodes.machine.image.fileName}",

        "-F",

        "raw",

        tmp_disk_image.name,