Minor change to semaphore test

tests/semaphores.py

@@ -2,7 +2,6 @@ import structio
 
 
 async def child(i: int, sem: structio.Semaphore):
-    print(f"[child {i}] I'm alive!")
     async with sem:
         print(f"[child {i}] Entered critical section")
         await structio.sleep(1)
@@ -28,4 +27,4 @@ async def main(n: int, k):
 
 
 # Should exit in about k seconds
-structio.run(main, 3, 2)
+structio.run(main, 3, 5)