poetry entrypoint to be able to just run a command within the poetry shell (like pytest in CI or something similar). Makes `poetry shell` actually behave like a shell and can be used as ENTRYPOINT in a docker container and it wil behave like a bash entrypoint

poetry_entrypoint.sh

#!/usr/bin/env bash
COMMAND=$@
set -x

command -v poetry > /dev/null || (echo missing poetry && exit 3)

if [[ -v ${COMMAND} ]]; then
    poetry shell
else
    bash -c ". .venv/bin/activate && $(printf ' %q' "$@")"
fi

NOTE. Just realized that you can use poetry run for the case you use a command
and for docker you can even use

ENTRYPOINT [ "/usr/bin/poetry", "run", "bash", "-c" ]
CMD [ "bash" ]

to get it to behave like poetry_entrypoint.sh above