fix(app): use group in dynamic k8s client

[olevski]

Some recent issues were possibly related to this.

It was never confirmed whether this would have helped or not. But it is still a good idea to use the API group if available to avoid confusion and problems in the future.

I checked the python k8s client and when the group is not passed in to the resource.get function it defaults to None

[olevski]

Just for reference this is the error that prompted this PR:

{"message": "Handler 'update_status' failed with an exception. Will ignore.", "exc_info": "Traceback (most recent call last):\n  File \"/app/controller/utils.py\", line 199, in get_api\n    return api_cache[(api_version, kind)]\n  File \"/us
r/local/lib/python3.8/site-packages/expiringdict/__init__.py\", line 77, in __getitem__\n    item = OrderedDict.__getitem__(self, key)\nKeyError: ('v1alpha1', 'JupyterServer')\n\nDuring handling of the above exception, another exception occu
rred:\n\nTraceback (most recent call last):\n  File \"/usr/local/lib/python3.8/site-packages/kopf/_core/actions/execution.py\", line 283, in execute_handler_once\n    result = await invoke_handler(\n  File \"/usr/local/lib/python3.8/site-pac
kages/kopf/_core/actions/execution.py\", line 378, in invoke_handler\n    result = await invocation.invoke(\n  File \"/usr/local/lib/python3.8/site-packages/kopf/_core/actions/invocation.py\", line 140, in invoke\n    await asyncio.shield(fu
ture)  # slightly expensive: creates tasks\n  File \"/usr/local/lib/python3.8/concurrent/futures/thread.py\", line 57, in run\n    result = self.fn(*self.args, **self.kwargs)\n  File \"/app/controller/server_controller.py\", line 282, in upd
ate_status\n    custom_resource_api = get_api(config.api_version, config.custom_resource_name)\n  File \"/app/controller/utils.py\", line 202, in get_api\n    api_cache[(api_version, kind)] = client.resources.get(\n  File \"/usr/local/lib/py
thon3.8/site-packages/kubernetes/dynamic/discovery.py\", line 211, in get\n    raise ResourceNotFoundError('No matches found for {}'.format(kwargs))\nkubernetes.dynamic.exceptions.ResourceNotFoundError: No matches found for {'api_version': '
v1alpha1', 'kind': 'JupyterServer'}", "timestamp": "2022-03-30T13:42:18.225715+00:00", "object": {"apiVersion": "v1", "kind": "PersistentVolumeClaim", "name": "tasko-2eol-test-2dpinned-2dimage-2d-4b1037c7", "uid": "0b5b36fa-57a6-480d-88c0-f9
c2b2b3a521", "namespace": "ci-renku-2534"}, "severity": "error"}

[ableuler]

Definitely an improvement, even if it should not fix the problem we've seen. 👍