importlib-metadata dependency error

[nailend]

I just ran into a pip package dependency conflict and couldn't start airflow using the current CI-branch:

pkg_resources.DistributionNotFound: The 'importlib-metadata~=2.0; python_version < "3.9"' distribution was not found and is required by apache-airflow

I downgraded to importlib-metadata==2

Found existing installation: importlib-metadata 4.11.1
    Uninstalling importlib-metadata-4.11.1:
      Successfully uninstalled importlib-metadata-4.11.1
ERROR: pip's dependency resolver does not currently take into account all the packages that are installed. This behaviour is the source of the following dependency conflicts.
sphinx 4.4.0 requires importlib-metadata>=4.4; python_version < "3.10", but you have importlib-metadata 2.0.0 which is incompatible.
Successfully installed importlib-metadata-2.0.0

Which will probably end up in errors with sphinx but airflow starts again.

[gnn]

PR #692 should fix this. Would you mind testing whether this is correct?