traceback on sync with new namespace "user" field

[jctanner]

pulp-ansible==0.19.0 and main ...

https://issues.redhat.com/browse/AAH-2721

We're adding a new field for "users" to the namespace serializer in galaxy_ng. When more recent pulp_ansible versions sync from such a system, they traceback on an unexpected field when creating a new namespace...

pulp [9ac390ffb6a7466faeb16dc66bc7e7db]: pulpcore.tasking.tasks:INFO: Task 018ace1c-2c92-7788-9072-8b8611c5ac5e failed (AnsibleNamespaceMetadata() got unexpected keyword arguments: 'users')
pulp [9ac390ffb6a7466faeb16dc66bc7e7db]: pulpcore.tasking.tasks:INFO:   File "/usr/local/lib/python3.11/site-packages/pulpcore/tasking/tasks.py", line 66, in _execute_task
    result = func(*args, **kwargs)
             ^^^^^^^^^^^^^^^^^^^^^

  File "/usr/local/lib/python3.11/site-packages/pulp_ansible/app/tasks/collections.py", line 191, in sync
    repo_version = d_version.create()
                   ^^^^^^^^^^^^^^^^^^

  File "/usr/local/lib/python3.11/site-packages/pulpcore/plugin/stages/declarative_version.py", line 161, in create
    loop.run_until_complete(pipeline)

  File "/usr/lib64/python3.11/asyncio/base_events.py", line 653, in run_until_complete
    return future.result()
           ^^^^^^^^^^^^^^^

  File "/usr/local/lib/python3.11/site-packages/pulpcore/plugin/stages/api.py", line 220, in create_pipeline
    await asyncio.gather(*futures)

  File "/usr/local/lib/python3.11/site-packages/pulpcore/plugin/stages/api.py", line 41, in __call__
    await self.run()

  File "/usr/local/lib/python3.11/site-packages/asgiref/sync.py", line 534, in thread_handler
    raise exc_info[1]

  File "/usr/local/lib/python3.11/site-packages/pulp_ansible/app/tasks/collections.py", line 1072, in run
    await asyncio.gather(*tasks)

  File "/usr/local/lib/python3.11/site-packages/pulp_ansible/app/tasks/collections.py", line 1012, in _find_all_collections
    await asyncio.gather(*tasks)

  File "/usr/local/lib/python3.11/site-packages/pulp_ansible/app/tasks/collections.py", line 866, in _fetch_collection_metadata
    await self._fetch_paginated_collection_metadata(

  File "/usr/local/lib/python3.11/site-packages/pulp_ansible/app/tasks/collections.py", line 809, in _fetch_paginated_collection_metadata
    await asyncio.gather(*tasks)

  File "/usr/local/lib/python3.11/site-packages/pulp_ansible/app/tasks/collections.py", line 598, in _fetch_collection_version_metadata
    await self._add_collection_version(api_version, collection_version_url, metadata)

  File "/usr/local/lib/python3.11/site-packages/pulp_ansible/app/tasks/collections.py", line 688, in _add_collection_version
    if await self._add_namespace(namespace, namespace_sha):
       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

  File "/usr/local/lib/python3.11/site-packages/pulp_ansible/app/tasks/collections.py", line 741, in _add_namespace
    namespace = AnsibleNamespaceMetadata(**namespace)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

  File "/usr/local/lib/python3.11/site-packages/django_lifecycle/mixins.py", line 61, in __init__
    super().__init__(*args, **kwargs)

  File "/usr/local/lib/python3.11/site-packages/django/db/models/base.py", line 567, in __init__
    raise TypeError(