shout2send: Unref event at the end of the event function

The function takes ownership of it and should get rid of it at the end.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/7992>

subprojects/gst-plugins-good/ext/shout2/gstshout2.c

@@ -491,6 +491,8 @@ gst_shout2send_event (GstBaseSink * sink, GstEvent * event)
     }
   }
 
+  gst_event_unref (event);
+
   return ret;
 }