Update Python library for compatibility with Python 3.12

[benfulton]

As of 3.12, the DistUtils library that is used to install the Python packages has been removed, so an install on a system without that package installed specifically will fail. A modern approach would be to use the setuptools package and move the specifics of the package to a file called "pyproject.toml". This will require Python 3.8 as a minimum version. I propose changing the version number to 0.2 and setting the project attributes as below. Let me know if I should change anything!

[project]
name = "fluidity"
version = "0.2"
description = "Required Python files for Fluidity, a multi-phase CFD code"
requires-python = ">=3.8"
authors = [
    {name = "Patrick Farrell"},
    {name = "Stephan Kramer"}
]
maintainers = [
    {name = "Ben Fulton"},
]
license = {text = "See LICENSE file"}
classifiers = [
    "Development Status :: 5 - Production",
    "Intended Audience :: Science/Research",
    "License :: Other/Proprietary License",
    "Operating System :: OS Independent",
    "Programming Language :: Python :: 3",
    "Programming Language :: Python :: 3.8",
    "Programming Language :: Python :: 3.9",
    "Programming Language :: Python :: 3.10",
    "Programming Language :: Python :: 3.11",
    "Programming Language :: Python :: 3.12",
    "Topic :: Scientific/Engineering",
]

[project.urls]
Homepage = "https://fluidity-project.org"
Documentation = "https://figshare.com/articles/journal_contribution/Fluidity_Manual/1387713?file=2031637"
Repository = "https://github.com/FluidityProject/fluidity"
Issues = "https://github.com/FluidityProject/fluidity/issues"