build this with the default node instead of pinning one

pkgs/kak-ayu/node.nix

@@ -1,8 +1,7 @@
 # This file has been generated by node2nix 1.9.0. Do not edit!
 
-{pkgs ? import <nixpkgs> {
-    inherit system;
-  }, system ? builtins.currentSystem, nodejs ? pkgs."nodejs-12_x"}:
+{ pkgs ? import <nixpkgs> { inherit system; }, system ? builtins.currentSystem
+, nodejs ? pkgs.nodejs }:
 
 let
   nodeEnv = import ./node-env.nix {
@@ -10,8 +9,7 @@ let
     inherit pkgs nodejs;
     libtool = if pkgs.stdenv.isDarwin then pkgs.darwin.cctools else null;
   };
-in
-import ./node-packages.nix {
+in import ./node-packages.nix {
   inherit (pkgs) fetchurl nix-gitignore stdenv lib fetchgit;
   inherit nodeEnv;
 }