Adopt a more modern Python build process

[bug-or-feature]

I propose to fully adopt pyproject.toml for building, dependency declaration, and tooling. This would mean

• adding new attributes licence and requires-python
• adding the list of dependencies
• adding a separate list of development dependencies
• adding a table for specifying package-data (all the CSV, YAML files)
• removing the file setup.py
• removing the file requirements.txt
• removing the file requirements_apple_silicon.txt
• removing the file install_dependencies_apple_silicon.txt
• updating the README and docs with up to date install instructions
• updating the github actions

It would be a phased change: first add deprecation warnings for the old way. After a few release cycles, remove the old way completely.

It would make sense to also remove tox.ini and .travis.yml - they are no longer used

Any thoughts, comments, objections?

[jurriaantressel]

You need not even remove the setup.py, it can be minimized to something such as

import setuptools

setuptools.setup()

See https://packaging.python.org/en/latest/guides/modernize-setup-py-project/#what-if-something-that-can-not-be-changed-expects-a-setup-py-file