As @saimn mentioned in #9729, and as mentioned in APE 17, there are two main ways of specifying the package data, both of them mentioned in the setuptools docs:

https://setuptools.readthedocs.io/en/latest/setuptools.html#including-data-files

Essentially, we can either define the package data in setup.cfg, or we can use the MANIFEST.in and then just set include_package_data=True in setup.cfg. I don't have very strong opinions, but MANIFEST.in might give us more flexibility in terms of e.g. including data files recursively.

Do people have strong opinions one way or another?