Update tests and whatsnew for the 'quiet' flag
diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index 92b7c42..50f0e93 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -501,7 +501,7 @@
         attrs = ("debug", "division_warning",
                  "inspect", "interactive", "optimize", "dont_write_bytecode",
                  "no_user_site", "no_site", "ignore_environment", "verbose",
-                 "bytes_warning")
+                 "bytes_warning", "quiet")
         for attr in attrs:
             self.assertTrue(hasattr(sys.flags, attr), attr)
             self.assertEqual(type(getattr(sys.flags, attr)), int, attr)