Remove unused imports in tests (GH-14518)

diff --git a/Lib/test/test_smtplib.py b/Lib/test/test_smtplib.py
index fdcf6f2..f1332e9 100644
--- a/Lib/test/test_smtplib.py
+++ b/Lib/test/test_smtplib.py
@@ -19,7 +19,7 @@
 
 import unittest
 from test import support, mock_socket
-from test.support import HOST, HOSTv4, HOSTv6
+from test.support import HOST
 from test.support import threading_setup, threading_cleanup, join_thread
 from unittest.mock import Mock