Add support for spotify client.

I like it way better than the browser client.

nalai/configuration.nix

@@ -113,6 +113,10 @@
   programs.neovim.enable = true;
   programs.neovim.defaultEditor = true;
 
+  nixpkgs.config.allowUnfreePredicate = pkg: builtins.elem (lib.getName pkg) [
+    "spotify"
+  ];
+  
   # List packages installed in system profile. To search, run:
   # $ nix search wget
   environment.systemPackages = with pkgs; [
@@ -122,8 +126,9 @@
     fish
     gimp-with-plugins
     git
-    python3
     neovim
+    python3
+    spotify
     thunderbird
     tmux
   ];