fix zeroconf_port config entry (#480)

The macro responsible for merging the CLI arguments and config file entries wasn't configured to take the `zeroconf_port` into consideration

src/config.rs

@@ -444,6 +444,7 @@ impl SharedConfigValues {
             volume_controller,
             cache_path,
             on_song_change_hook,
+            zeroconf_port,
             proxy
         );