test_relate fails on 3.3, 3.4, 3.5, 3.6

[james-garner-canonical]

Description

test_relate currently fails on all the Juju versions we test other than 3.1. Example failures: 3.3, 3.4, 3.5, 3.6).

test_relate errors on L746 when attempting to deploy the nrpe charm:

        await model.deploy(
            "nrpe",
            application_name="nrpe",
            base="ubuntu@20.04/stable",
            channel="stable",
            # subordinates must be deployed without units
            num_units=0,
        )

The relevant traceback is:

  File "/home/runner/work/python-libjuju/python-libjuju/tests/integration/test_model.py", line 746, in test_relate
    await model.deploy(
  File "/home/runner/work/python-libjuju/python-libjuju/juju/model/__init__.py", line 1999, in deploy
    return await self._deploy(
  File "/home/runner/work/python-libjuju/python-libjuju/juju/model/__init__.py", line 2376, in _deploy
    raise JujuError("\n".join(errors))
juju.errors.JujuError: base "ubuntu@20.04/stable" is not supported, supported bases are: ubuntu@24.04

The nrpe charm appears to still support 20.04, and I'm not sure why this test consistently doesn't fail with Juju 3.1.

Urgency

Casually reporting

Python-libjuju version

main

Juju version

3.3,3.4,3.5,3.6

Reproduce / Test

test_relate()