Fix unused lambda capture in SimpleActorTest

tests/SimpleActorTest.cpp

@@ -41,7 +41,7 @@ static void mainFiber(void* runtime_ptr) {
 
 	CPS cps;
 	for (unsigned int i = 0; i < FIBER_COUNT; ++i) {
-		spawn([&sumActor, i] {
+		spawn([&sumActor] {
 				WDBG(Dispatcher::getCurrentFiber() << " starts to count to " << FIBERS_COUNT_TO);
 				for (uint64_t i = 1; i <= FIBERS_COUNT_TO; ++i) {
 					sumActor.tell(i);