nixos/tailscale: use networking.resolvconf.package

Allow using the appropriate resolver implementation to set DNS entries
(typically systemd-resolved instead of openresolv).

nixos/modules/services/networking/tailscale.nix

@@ -46,7 +46,7 @@ in {
     systemd.services.tailscaled = {
       wantedBy = [ "multi-user.target" ];
       path = [
-        pkgs.openresolv # for configuring DNS in some configs
+        config.networking.resolvconf.package # for configuring DNS in some configs
         pkgs.procps     # for collecting running services (opt-in feature)
         pkgs.glibc      # for `getent` to look up user shells
       ];