Improve python packaging: setuptools, poetry

Drop problematic minver support.

Use single-source __version__ from apkg/__init__.py.

Use more robust method of reading __version__ from setup.py when using
setuptools.

Make scripts/make-archive.sh update __version__ using Dunamai tool from
git - PEP 440 compatible.

Add poetry support with poetry-dynamic-versioning plugin providing
dynamic versioning using Dunamai including __version__ updates.