Fix the `include` directives in `pyproject.toml` to include the relevant
files in `sdist` archives only and not in wheels, where they end up
being installed straight into site-packages, e.g. as:

    /usr/lib/python3.12/site-packages/CHANGELOG.md
    /usr/lib/python3.12/site-packages/README.md

Do not invoke the executable via `poetry` in tests, as it is redundant
and introduces unnecessary dependency on `poetry` when the package
is installed via PEP517 installer or `tox`.  When using `poetry`, one
needs to explicitly execute `poetry install` anyway and this causes
the executable to be installed.  Furthermore, the common way of running
pytest via poetry is to execute:

    poetry run pytest

causing nesting in CLI tests.

fix pyproject.toml not to install stray files into site-packages

Test fixes