Explicity unsubscribe from time_ticker_service

src/c/main.c

@@ -390,6 +390,9 @@ static void init() {
 
 // free memory on app exit
 static void deinit() {
+	// unsubscribe
+	tick_timer_service_unsubscribe();
+
 	// destroy layers
 	text_layer_destroy(s_time_layer);
 	text_layer_destroy(s_date_layer);