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_ftplib.py b/Lib/test/test_ftplib.py
index a48b429..3492ba4 100644
--- a/Lib/test/test_ftplib.py
+++ b/Lib/test/test_ftplib.py
@@ -4,8 +4,6 @@
 # environment
 
 import ftplib
-import asyncore
-import asynchat
 import socket
 import io
 import errno
@@ -24,6 +22,13 @@
 from test.support import warnings_helper
 from test.support.socket_helper import HOST, HOSTv6
 
+import warnings
+with warnings.catch_warnings():
+    warnings.simplefilter('ignore', DeprecationWarning)
+    import asyncore
+    import asynchat
+
+
 TIMEOUT = support.LOOPBACK_TIMEOUT
 DEFAULT_ENCODING = 'utf-8'
 # the dummy data returned by server over the data channel when