gh-130736: Fix asyncio test_shutdown_default_executor_timeout()

Use a ridiculous small timeout (1 nanosecond) instead of 10 ms.

Author: vstinner

Lib/test/test_asyncio/test_base_events.py

@@ -246,7 +246,7 @@ def shutdown(self, wait=True, *, cancel_futures=False):
         with self.assertWarnsRegex(RuntimeWarning,
                                    "The executor did not finishing joining"):
             self.loop.run_until_complete(
-                self.loop.shutdown_default_executor(timeout=0.01))
+                self.loop.shutdown_default_executor(timeout=1e-9))
 
     def test_call_soon(self):
         def cb():