chore(build): migrate to pyproject.toml for packaging

[SauravMaheshkar]

🚀 Feature

pyproject.toml is the new standard for packaging python packages, setup.py is now deprecated (first introduced in PEP 518 and later expanded in PEP 517, PEP 621 and PEP 660). This issue proposes to switch from the legacy setup.py method in favour of pyproject.toml. This would lead to a overall better project structure because we would have one single pyproject.toml file instead of 3 separate setup.cfg, .yapfignore and setup.py files. It also allows for dynamic version allocation (reads automatically from /__init__.py).

Happy to take this up 😄