Update pyproject.toml

[eleftherioszisis]

Add build-system entry as per https://setuptools.pypa.io/en/latest/build_meta.html

Reverted (See below for details):
Switch to preferred way to configure setuptools_scm

[eleftherioszisis]

Unfortunately, I discovered that switching to the pyproject.toml configuration is not equivalent to using the setup.py as far as setuptools_scm is concerned.

setup.py commands do not install build dependencies from pyproject.toml, therefore if python setup.py --version is executed, it will silently return 0.0.0 with the pyproject.toml configuration unless the latest setuptools_scm[toml] and setuptools are already installed. Tox will also fail to get the version correctly for the same reason.

I will revert to the old way, as it is the most robust for the time being. Otherwise, we would need to add the dependencies in many places, such as in a setup.cfg and in tox.ini.

For more details, see:
pypa/setuptools-scm#386 (comment)

[adrien-berchet]

Unfortunately, I discovered that switching to the pyproject.toml configuration is not equivalent to using the setup.py as far as setuptools_scm is concerned.

Ah 🤦