Migrate to pyproject.toml

[sr-murthy]

@Brooke-white Given PYPA recommends moving from setup.py to pyproject.toml, would you consider an MR to migrate? This would involve replacing setup.py, setup.cfg, as well as the requirements files, with pyproject.toml, and using a build tool such as PDM? I've done the migration in other projects, and it works pretty well, and produce equivalent results.