migrating project metadata from setup.py to pyproject.toml

[donn-chadh]

Modernised the repo's build config by moving static metadata from .py file to .toml file.

• config metadata fields (name, authors, classifiers etc) using PEP 621 layout
• set up dynamic versioning mapping back to the existing package source.
• left the original custom cmdclass handlers (Publish, RunTests) intact inside setup.py so exsisting workflows remain unaffected.
• successfully verified the install locally using editable mode (pip install -e .)