bpo-44498: suppress DeprecationWarnings for asynchat, asyncore and smtpd in tests (GH-26905) (GH-26907)

(cherry picked from commit 22e7effad571f8e524d2f71ff55bbf2a25306753)

Co-authored-by: Irit Katriel <1055913+iritkatriel@users.noreply.github.com>
diff --git a/Lib/test/test_poplib.py b/Lib/test/test_poplib.py
index c5ae9f7..8dd6ea6 100644
--- a/Lib/test/test_poplib.py
+++ b/Lib/test/test_poplib.py
@@ -4,8 +4,6 @@
 # a real test suite
 
 import poplib
-import asyncore
-import asynchat
 import socket
 import os
 import errno
@@ -17,6 +15,12 @@
 from test.support import socket_helper
 from test.support import threading_helper
 
+import warnings
+with warnings.catch_warnings():
+    warnings.simplefilter('ignore', DeprecationWarning)
+    import asynchat
+    import asyncore
+
 HOST = socket_helper.HOST
 PORT = 0