Assertion in test_tls_ext_noca breaks with OpenSSL 1.1

The assertion in test https://github.com/python-ldap/python-ldap/blob/master/Tests/t_cext.py#L815-L823 fails when libldap is compiled with OpenSSL 1.1

```
AssertionError: 'not trusted' not found in "{'desc': 'Connect error', 'info': 'error:1416F086:SSL routines:tls_process_server_certificate:certificate verify failed (self signed certificate in certificate chain)'}"
```