Jenkinsfile.integration: use python3.11 for jcs

[kshtsk]

It appears in the newer openstackclient code the new feature available starting from Python 3.7:

  from __future__ import annotations

For more info see:
https://peps.python.org/pep-0563/#enabling-the-future-behavior-in-python-3-7

Since the default Python in Leap 15.4 is still 3.6, so maybe just start using the latest available 3.11 for jcs.

[kshtsk]

@tserong

    master: ++ ceph-salt --version

    master: ceph-salt 16.2.4

    master: ++ salt -G ceph-salt:member state.apply ceph-salt

    master: ERROR: Minions returned with non-zero exit code

    master: master.mini.test:

    master:     Minion did not return. [No response]

    master:     The minions may not have all finished running and any remaining minions will return upon completion. To look up the return data for this job later, run the following command:

    master: 

    master:     salt-run jobs.lookup_jid 20230626142659772098

Something in test. I recommend to merge this PR it does not touch the code where the test failing.

[tserong]

Something in test. I recommend to merge this PR it does not touch the code where the test failing.

Yeah, that's that irritating intermittent problem I've been trying to hunt down, and is unrelated to this fix.

Thanks!