fix qbittorrent on lutea

modules/qbittorrent.nix

···
               AuthSubnetWhitelistEnabled = true;
               AuthSubnetWhitelist = lib.strings.join ", " [
                 "192.168.2.1"
-                (lib.optionals (config.networking.hostName == "lily") config.garden.info.network.lutea.netbird-ip)
+                (lib.optionalString (config.networking.hostName == "lily") config.garden.info.network.lutea.netbird-ip)
               ];
             };
           };