Replace setup.py with build

[jdufresne]

Using setup.py is no longer recommended by setuptools. Instead, projects
should use build: https://github.com/pypa/build. Invoking build will
create a source and wheel distribution
https://pypa-build.readthedocs.io/en/latest/:

By default, a source distribution (sdist) is built from {srcdir} and a
binary distribution (wheel) is built from the sdist.

See the setuptools quickstart guides for more information:
https://setuptools.pypa.io/en/latest/userguide/quickstart.html

Instead, when creating new Python packages, it is recommended to use a
command line tool called build. This tool will automatically download
setuptools and any other build-time dependencies that your project
might have. You just need to specify them in a pyproject.toml file at
the root of your package, as indicated in the following section.