ci: increase timeout threshold to solve deepsleep wakestub example ci failure

examples/system/deep_sleep_wake_stub/pytest_deep_sleep_wake_stub.py

@@ -22,7 +22,7 @@ def test_deep_sleep_wake_stub(config: str, dut: Dut) -> None:
 
         start_sleep = time.time()
         logging.info('Waiting for wakeup...')
-        dut.expect_exact('wake stub: going to deep sleep')
+        dut.expect_exact('wake stub: going to deep sleep', timeout=15)
 
         sleep_time = time.time() - start_sleep
         logging.info('Host measured sleep time at {:.2f}s'.format(sleep_time))