python: add MANIFEST.in

python: add MANIFEST.in

When creating a source or binary distribution via 'python3 setup.py
<sdist|bdist>', the VERSION and PACKAGE.rst files aren't bundled by
default. Create a MANIFEST.in file that instructs the build tools to
include these so that installation from these files won't fail.

This is required by 'tox', as well as by the tooling needed to upload
packages to PyPI.

Exclude the 'README.rst' file -- that's intended as a guidebook to our
source tree, not a file that needs to be distributed.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Cleber Rosa <crosa@redhat.com>
Message-id: 20210527211715.394144-14-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>