Move from setuptools to pyproject.toml

[adamfowleruk]

There is a deprecation warning when compiling OpenABM currently:-

DEPRECATION: covid19 is being installed using the legacy 'setup.py install' method, because it does not have a 'pyproject.toml' and the 'wheel' package is not installed. pip 23.1 will enforce this behaviour change. A possible replacement is to enable the '--use-pep517' option. Discussion can be found at https://github.com/pypa/pip/issues/8559

The latest version is already at 23.2.1 and so this will already be affecting those on recent versions of python.

I'm happy to create one of these for the project myself, but I'm opening this issue for wider awareness.