remove nix-bitcoin.pkgs.lib

Type ipv4Address is not needed anymore because all services have
separate 'port' and 'address' options.

pkgs/default.nix

@@ -20,7 +20,5 @@ let self = {
 
   pinned = import ./pinned.nix;
 
-  lib = import ./lib.nix { inherit (pkgs) lib; };
-
   modulesPkgs = self // self.pinned;
 }; in self

pkgs/lib.nix

@@ -1,5 +0,0 @@
-{ lib }:
-{
-  # An address type that checks that there's no port
-  ipv4Address = lib.types.addCheck lib.types.str (s: builtins.length (builtins.split ":" s) == 1);
-}