UI: Reserve correct number of elements in vector

UI/window-basic-main.cpp

@@ -433,7 +433,7 @@ static obs_data_t *GenerateSaveData(obs_data_array_t *sceneOrder,
 	obs_data_t *saveData = obs_data_create();
 
 	vector<OBSSource> audioSources;
-	audioSources.reserve(5);
+	audioSources.reserve(6);
 
 	SaveAudioDevice(DESKTOP_AUDIO_1, 1, saveData, audioSources);
 	SaveAudioDevice(DESKTOP_AUDIO_2, 2, saveData, audioSources);