[NixOS] Remove nixpkgs and home manager submodules

.gitmodules

@@ -7,9 +7,3 @@
 [submodule "dotfiles/xmonad/xmonad-contrib"]
 	path = dotfiles/config/xmonad/xmonad-contrib
 	url = ../xmonad-contrib.git
-[submodule "nixos/home-manager"]
-	path = nixos/home-manager
-	url = git@github.com:IvanMalison/home-manager.git
-[submodule "nixos/nixpkgs"]
-	path = nixpkgs
-	url = git@github.com:IvanMalison/nixpkgs.git

nixos/flake.nix

@@ -3,7 +3,7 @@
     nixos-hardware = { url = github:NixOS/nixos-hardware; };
 
     nixpkgs = {
-      url = path:../nixpkgs;
+      url = github:NixOS/nixpkgs/nixos-unstable;
     };
 
     home-manager = {