Chore: add back amplify of fallback

src/in_fallback.liq

@@ -81,7 +81,7 @@ def attach_fallback_source(main_stream) =
           reload_mode="seconds"
         )
 
-      # s = amplify(id="fallback_folder", 1., override="replay_gain", s)
+      s = amplify(id="fallback_folder", 1., override="replay_gain", s)
 
       # s = replaygain(s)
       s = source.on_track(id="fallback_folder", s, on_fallback_notify)