Modernize 🧑‍🔬 (build sys, pypi classifier,dependencies, unit testing, contrib.md, pre-com hooks, lint, semantic rels)

[cneskey]

• [ ] move to modern build system and packaging standards (poetry, pdm; pyproject.toml)
• [ ] update pypi classifier list to declare supported python versions (3.8+)
• [ ] upgrade dated dependencies and ensure compatibility
• [ ] move to modern unit testing framework (pytest)
• [ ] add CONTRIBUTING.md
• [ ] add pre-commit hooks
• [ ] enforce black/ruff formatting
• [ ] enforce conventional commits and use semantic release