Switch to a Poetry build-backend

Requires: !66 (merged) to be merged first

The main reason for switching to poetry is the ability to add local dependencies because in the case of the 'dev' environment, we need to install additional packages for tests named local-tools.

Standard setuptools do not provide this option.
https://github.com/pypa/setuptools/discussions/2951

Also, poetry is a build back-end that fully supports for PEP 621, as setuptools currently have experimental support. This allows us to go to a single installation file pyproject.toml and remove setup.py and setup.cfg