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_smtplib.py b/Lib/test/test_smtplib.py
index f3d33ab..483d747 100644
--- a/Lib/test/test_smtplib.py
+++ b/Lib/test/test_smtplib.py
@@ -1,4 +1,3 @@
-import asyncore
 import base64
 import email.mime.text
 from email.message import EmailMessage
@@ -7,7 +6,6 @@
 import hashlib
 import hmac
 import socket
-import smtpd
 import smtplib
 import io
 import re
@@ -25,6 +23,12 @@
 from test.support import threading_helper
 from unittest.mock import Mock
 
+import warnings
+with warnings.catch_warnings():
+    warnings.simplefilter('ignore', DeprecationWarning)
+    import asyncore
+    import smtpd
+
 HOST = socket_helper.HOST
 
 if sys.platform == 'darwin':