Add a delay for FT builds

Author: YvesDup

Lib/test/test_threading.py

@@ -1474,6 +1474,9 @@ def _set_ident_error():
             thread._set_ident = _set_ident_error
             thread.start()
 
+        # Give the thread a moment to clean up after itself
+        # specially in free-threading builds.
+        time.sleep(0.1)
         self.assertFalse(thread.is_alive())
         self.assertFalse(thread in threading._limbo)
         self.assertFalse(thread in threading._active)