Switch to pyproject.toml

[Ayush1325]

Since PEP 621, pyproject.toml is the standard way of specifying project metadata. This patch simply migrates everything in setup.py to pyproject.toml

Link: https://peps.python.org/pep-0621/ PEP 621

[Hedda]

Guess an option could be to also keep setup.py file for backwards compatiobility and have this in it as seen other projects do, or?

"""Setup file for cc2538-bsl."""

import setuptools

if __name__ == "__main__":
    setuptools.setup()