fix: install additional packages

Installed the following packages:

- deno
- neovim from the unstable channel.

configuration.nix

@@ -47,8 +47,14 @@
   # Configure console keymap
   console.keyMap = "uk";
 
-  # Allow unfree packages
+  nixpkgs = {
-  nixpkgs.config.allowUnfree = true;
+    config = {
+      allowUnfree = true;
+      packageOverrides = pkgs: {
+        unstable = import (fetchTarball "https://github.com/NixOS/nixpkgs/archive/nixos-unstable.tar.gz") {};
+      };
+    };
+  };
 
   # Enable sound with pipewire.
   sound.enable = true;
@@ -66,6 +72,7 @@
   environment = {
     systemPackages = with pkgs; [
       curl
+      deno
       distrobox
       firefox
       gcc
@@ -167,8 +174,8 @@
     description  = "Dan Anglin";
     extraGroups  = [ "networkmanager" "wheel" "docker"];
     packages = with pkgs; [
-      neovim
       lf
+      unstable.neovim
     ];
   };