fix: do not pass config to nixpgks in nixosConfigurations transformer

[truelecter]

Recent changes in nixpkgs favor pkgs.config instead of nixpkgs.config and while setting will throw an error. With previous behavior, nixpkgs.config was silently ignored if pkgs.config were present.

We can just skip passing the config to the nixpkgs, because we already define pkgs.

See: NixOS/nixpkgs#257458, NixOS/nixpkgs#258447

[Lord-Valen]

This is a duplicate of #26.

[truelecter]

Rly, my bad

[blaggacao]

Thanks nevertheless! 😄