[freeipa PR#5118][opened] test_smb: mark test_smb_service_s4u2self as xfail for fed31

[flo-renaud]

   URL: https://github.com/freeipa/freeipa/pull/5118
Author: flo-renaud
 Title: #5118: test_smb: mark test_smb_service_s4u2self as xfail for fed31 
Action: opened

PR body:
"""
The test test_integration/test_smb.py::TestSMB::test_smb_service_s4u2self
is expected to fail in Fedora <= 31 as it requires krb >= 1.18
that is shipped from fedora 32 only

Mark the test as conditionally failing depending on the fedora version.

Fixes: https://pagure.io/freeipa/issue/8505
"""

To pull the PR as Git branch:
git remote add ghfreeipa https://github.com/freeipa/freeipa
git fetch ghfreeipa pull/5118/head:pr5118
git checkout pr5118