Fix Pytest4.x warning about message

"message" parameter of pytest.raises is deprecated since Pytest4.1:
```
It is a common mistake to think this parameter will match the
exception message, while in fact it only serves to provide a custom
message in case the pytest.raises check fails.
```

That was the truth for test_unrecognised_attr_type_raises, which has
wrongly checked an exception message.

Fixes: https://pagure.io/freeipa/issue/7981
Signed-off-by: Stanislav Levin <slev@altlinux.org>
Reviewed-By: Christian Heimes <cheimes@redhat.com>

ipatests/test_ipaclient/test_csrgen.py

@@ -259,7 +259,7 @@ class test_CSRGenerator:
 
         with pytest.raises(
                 errors.CSRTemplateError,
-                message='unrecognised attribute type: X'):
+                match=r'^unrecognised attribute type: X$'):
             csrgen_ffi.build_requestinfo(
                 config.encode('utf-8'), adaptor.get_subject_public_key_info())