UI: Fix memory leak when saving stream settings

SetService started using addref in
71abed387fe465b7a9defbd6b0dadd71e28d533f, so we have to release
the extra reference here

obs/window-basic-settings.cpp

@@ -1870,6 +1870,7 @@ void OBSBasicSettings::SaveStream1Settings()
 
 	main->SetService(newService);
 	main->SaveService();
+	obs_service_release(newService);
 }
 
 void OBSBasicSettings::SaveVideoSettings()