add newline at end of startImmediately.swift file

Author: ktoso

test/Concurrency/Runtime/startImmediately.swift

@@ -563,4 +563,4 @@ func call_taskImmediate_taskExecutor(taskExecutor: NaiveQueueExecutor) async {
 await call_taskImmediate_taskExecutor(
   taskExecutor: NaiveQueueExecutor(queue: DispatchQueue(label: "my-queue")))
 
-print("DONE!") // CHECK: DONE!
+print("DONE!") // CHECK: DONE!