bpo-31235: Fix ResourceWarning in test_logging (#3147)

diff --git a/Lib/test/test_logging.py b/Lib/test/test_logging.py
index 226532a..f4aef9f 100644
--- a/Lib/test/test_logging.py
+++ b/Lib/test/test_logging.py
@@ -797,6 +797,8 @@
             """
             self.close()
             self._thread.join(timeout)
+            asyncore.close_all(map=self._map, ignore_all=True)
+
             alive = self._thread.is_alive()
             self._thread = None
             if alive: