Switch to poetry-core

[cdgriffith]

#244 brought up by Michał Górny @mgorny

https://python-poetry.org/docs/pyproject/#poetry-and-pep-517

[cdgriffith]

killing off poetry for next version

[mgorny]

For the record, you can some of the same "feeling" (at least config-side) with modern setuptools pyproject.toml configs.