Standardize packaging system

[derekbarbosa]

DEPRECATION: yattag 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

Convert this project to use a more standard method of installation (pyproject.toml). This enables setup tools to be used on the backend, and have metadata configured via a .toml frontend.

While setup.py is not fully deprecated for the time being, convert the current setup.py project structure to include a pyproject.toml to prevent any deprecation (as demonstrated by this [guide] (https://packaging.python.org/en/latest/guides/modernize-setup-py-project/#modernize-setup-py-project)).

This will also allow for installation locally using pip install . and editable install using pip install -e .

Solves #79