switch to pyproject.toml for tools configuration

[ltalirz]

More and more tools support using the pyproject.toml file (PEP 518) for specifying their configuration.
Making use of this allows to unclutter the top level of the aiida-core repository and keep the configuration of these tools in one place.

Support for pyproject.toml in our tool chain:

• coverage >= 5.0
• pylint >= 2.5
• pytest (planned for release 5.5.)
• prospector, see [FEATURE REQUEST] support configuration in pyproject.toml prospector-dev/prospector#376 no longer used
• yapf, see Integration with pyproject.toml for Formatting style google/yapf#708
• mypy mypy/issues/5205
• readthedocs readthedocs.org/issues/7065 they decided not to support it

[greschd]

A good reference on the (build aspects of the) pyproject.toml file: https://snarky.ca/what-the-heck-is-pyproject-toml/

[csadorf]

It appears that pytest 6.0 (rc was released) will have support for pyproject.toml configurations: https://github.com/pytest-dev/pytest/releases/tag/6.0.0rc1

[greschd]

Pytest 6.0 proper is already out, see https://pypi.org/project/pytest/#history. The latest release is 6.0.1.

[csadorf]

Pytest 6.0 proper is already out, see https://pypi.org/project/pytest/#history. The latest release is 6.0.1.

Thx, I missed that.

[ltalirz]

@sphuber I guess you didn't see this issue, might be closed together with #4409

[sphuber]

I did see it, but yapf is still open. As well as a few others that I just added

[sphuber]

I am closing this since I recently added yapf and mypy to it.

[chrisjsewell]

Cheers @sphuber, and hopefully at some point we can ditch our setup.json/setup.py for it as well: pypa/setuptools#1688