Initial neuxml package

[rlskoeser]

minimal conversion to publish an initial version of our fork of eulxml on pypi

• remove eulxml.forms submodule
• rename eulxml to neuxml everywhere
• update/rewrite readme
• drop/truncate changelog
• github action for pypi publication
• decide on version number for first release

nice to have but maybe not necessary for a first release:

• pre-commit hooks / ruff formatting #9
• drop tox and switch to github actions #10
• migrate to pyproject.toml (replaces setup.cfg, setup.py, pip-dev-req.txt, and MANIFEST.in)

[rlskoeser]

Probably some part of #2 is also appropriate - at least dropping old versions of python and django