conda-forge package

[Thomas-Z]

I'm working on the conda-forge packaging, here are some feedbacks:

• There is a missing dependency in setup.cfg : pyarrow (used in zcollection.indexing.abc).
• Using setuptools_scm to dynamically define the version from git tags forces us to use pypi as source. The package cannot be build from a github archive which does not contain .git information.
• I think that not having the version number writen in pyproject.toml forces setuptools to import zcollection during the packaging build step which forces us to add all the run dependencies to the host part of the meta.yaml.

The conda-forge PR is here. @fbriol : Could you post a comment on this PR in order for me to check the following item of the check-list:

• [x] GitHub users listed in the maintainer section have posted a comment confirming they are willing to be listed there.

[fbriol]

I modified the setup.cfg file to read the version number directly from the module.