nixos-configuration/modules/_common/nixpkgs.nix

{...}: {
  config = {
    nixpkgs.config.allowUnfree = true;

    system = {
      stateVersion = "22.11";
      # enable auto updates
      autoUpgrade = {
        enable = true;
        dates = "weekly";
      };
    };

    nix.gc = {
      automatic = true;
      dates = "monthly";
      options = "--delete-older-than 30d";
    };
  };
}