Properly include "data packages" in project

[jwodder]

There is a folder in dandischema/ that contains data files but no Python source code, and we want this folder to be included when dandischema is installed. Currently, this folder is automatically included by the combination of graft dandischema in MANIFEST.in and include_package_data = True in setup.cfg, but because we set packages in setup.cfg to find: instead of find_namespace:, the folder itself is not recognized by setuptools as a package. This combination of settings is deprecated, and the setuptools developers recommend using find_namespace: instead of find: for such situations.

[codecov]

Codecov Report

Merging #138 (059b642) into master (148a18c) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #138   +/-   ##
=======================================
  Coverage   96.67%   96.67%           
=======================================
  Files          18       18           
  Lines        1654     1654           
=======================================
  Hits         1599     1599           
  Misses         55       55           

Flag	Coverage Δ
unittests	96.67% <ø> (ø)

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