wheel build issue with openeo.extra.spectral_indices.resources

I noticed this when doing python setup.py bdist_wheel with most recent setuptools/wheels packages locally (python 3.9 env):

...
reading manifest template 'MANIFEST.in'
adding license file 'LICENSE'
writing manifest file 'openeo.egg-info/SOURCES.txt'
/home/...../src/openeo/openeo-python-client/venv/lib/python3.9/site-packages/setuptools/command/build_py.py:202: SetuptoolsDeprecationWarning:     Installing 'openeo.extra.spectral_indices.resources' as data is deprecated, please list it in `packages`.
    !!


    ############################
    # Package would be ignored #
    ############################
    Python recognizes 'openeo.extra.spectral_indices.resources' as an importable package,
    but it is not listed in the `packages` configuration of setuptools.

    'openeo.extra.spectral_indices.resources' has been automatically added to the distribution only
    because it may contain data files, but this behavior is likely to change
    in future versions of setuptools (and therefore is considered deprecated).

    Please make sure that 'openeo.extra.spectral_indices.resources' is included as a package by using
    the `packages` configuration field or the proper discovery methods
    (for example by using `find_namespace_packages(...)`/`find_namespace:`
    instead of `find_packages(...)`/`find:`).

    You can read more about "package discovery" and "data files" on setuptools
    documentation page.


!!

  check.warn(importable)
/home/.../src/openeo/openeo-python-client/venv/lib/python3.9/site-packages/setuptools/command/install.py:34: SetuptoolsDeprecationWarning: setup.py install is deprecated. Use build and pip and other standards-based tools.
  warnings.warn(
installing to build/bdist.linux-x86_64/wheel
...

to be investigated further.

(I don't see this in jenkins runs, which is still(?) py 3.6)

Start by reproducing python setup.py bdist_wheel in a Python 3.9 environment with current setuptools and wheel versions. Inspect the package discovery configuration and MANIFEST.in for openeo.extra.spectral_indices.resources; done means the wheel builds without the deprecation warning and includes the resources package.