pylibjuju-3.1.0.1 not compatible with juju 2.9.42

[Bas de Bruijne]

As seen in https://solutions.qa.canonical.com/v2/testruns/07a4ebe0-6dc0-41aa-94a1-813ec53f9882, the pylibjuju version used for k8s 1.27 testing is not compatible with juju 2.9.42:

======================
2023-04-11-13:50:14 root DEBUG ==================================== ERRORS ====================================
2023-04-11-13:50:14 root DEBUG ______________ ERROR at setup of test_clusterip_service_endpoint _______________
2023-04-11-13:50:14 root DEBUG Traceback (most recent call last):
2023-04-11-13:50:14 root DEBUG File "/home/ubuntu/k8s-validation/.tox/py3/lib/python3.8/site-packages/pytest_asyncio/plugin.py", line 299, in _asyncgen_fixture_wrapper
2023-04-11-13:50:14 root DEBUG result = event_loop.run_until_complete(setup())
2023-04-11-13:50:14 root DEBUG File "/usr/lib/python3.8/asyncio/base_events.py", line 616, in run_until_complete
2023-04-11-13:50:14 root DEBUG return future.result()
2023-04-11-13:50:14 root DEBUG File "/home/ubuntu/k8s-validation/.tox/py3/lib/python3.8/site-packages/pytest_asyncio/plugin.py", line 281, in setup
2023-04-11-13:50:14 root DEBUG res = await gen_obj.__anext__()
2023-04-11-13:50:14 root DEBUG File "/home/ubuntu/k8s-validation/jobs/integration/conftest.py", line 258, in model
2023-04-11-13:50:14 root DEBUG await model.connect(tools.connection)
2023-04-11-13:50:14 root DEBUG File "/home/ubuntu/k8s-validation/.tox/py3/lib/python3.8/site-packages/juju/model.py", line 658, in connect
2023-04-11-13:50:14 root DEBUG _, model_uuid = await self._connector.connect_model(model_name, **kwargs)
2023-04-11-13:50:14 root DEBUG File "/home/ubuntu/k8s-validation/.tox/py3/lib/python3.8/site-packages/juju/client/connector.py", line 174, in connect_model
2023-04-11-13:50:14 root DEBUG await self.connect(**kwargs)
2023-04-11-13:50:14 root DEBUG File "/home/ubuntu/k8s-validation/.tox/py3/lib/python3.8/site-packages/juju/client/connector.py", line 82, in connect
2023-04-11-13:50:14 root DEBUG raise JujuConnectionError("juju server-version %s not supported" % juju_server_version)
2023-04-11-13:50:14 root DEBUG juju.errors.JujuConnectionError: juju server-version 2.9.42 not supported
2023-04-11-13:50:14 root DEBUG ------------------------------ Captured log setup ------------------------------
2023-04-11-13:50:14 root DEBUG WARNING connector:connector.py:80 This version was tested using 3.1.0 juju version 2.9.42 may have compatibility issues
2023-04-11-13:50:14 root DEBUG =============================== warnings summary ===============================
2023-04-11-13:50:14 root DEBUG .tox/py3/lib/python3.8/site-packages/invoke/loader.py:3
2023-04-11-13:50:14 root DEBUG /home/ubuntu/k8s-validation/.tox/py3/lib/python3.8/site-packages/invoke/loader.py:3: DeprecationWarning: the imp module is deprecated in favour of importlib; see the module's documentation for alternative uses
2023-04-11-13:50:14 root DEBUG import imp
2023-04-11-13:50:14 root DEBUG
======================

We need to come up with a way to validate ck8s 1.27 on juju 2.9.42 controllers

[Adam Dyess (addyess)]

Yes, this will be the first release that supports both juju 3.1 as well as continuing to support juju 3.0 and 2.9

There's a different requirements-2.9.txt in the repo to use when targeting a juju 2.9 controller

before starting the tests ensure you have the correct pip requirements installed

if bootstrapping a juju 2.9 controller:
pip-sync requirements-2.9.txt

if bootstrapping a later controller
pip-sync requirements.txt

```
source juju.bash
juju::pip::2.9
```