pythongh-115627: Fix ssl test_pha_required_nocert()

Accept also BrokenPipeError error message.

Author: vstinner

Lib/test/test_ssl.py

@@ -4537,7 +4537,7 @@ def msg_cb(conn, direction, version, content_type, msg_type, data):
                 # server aborts connection with an error.
                 with self.assertRaisesRegex(
                     OSError,
-                    'certificate required|EOF occurred|closed by the remote host|Connection reset by peer'
+                    'certificate required|EOF occurred|closed by the remote host|Connection reset by peer|Broken pipe'
                 ):
                     # receive CertificateRequest
                     data = s.recv(1024)