Don't depend on external nixos-unstable channel

modules can now use unstablePkgs argument

nix-os/shell.nix

@@ -1,7 +1,6 @@
-{ config, pkgs, ... }:
+{ config, pkgs, unstablePkgs, ... }:
 
 let
-  unstable = import <nixos-unstable> {};
   rangerGit = pkgs.ranger.overrideAttrs (old: {
     version = "git";
     src = pkgs.fetchFromGitHub {
@@ -20,6 +19,9 @@ let
   });
 in
 {
+  imports = [
+    ./unstable-packages.nix
+  ];
   environment.systemPackages = with pkgs; [
     rangerGit
     kitty
@@ -50,7 +52,7 @@ in
     set vcs_aware true
     set show_hidden true
 
-    alias drag shell ${unstable.ripdrag}/bin/ripdrag -Axd %p &
+    alias drag shell ${unstablePkgs.ripdrag}/bin/ripdrag -Axd %p &
     map <C-d> drag
   '';