Support for pyproject.toml

[davfsa]

This request is to add pyproject.toml support without the use of poetry or any external packages (just pip).

This was partially implemented back in back in 2018 with #635, which included support for poetry. But pyproject.toml was initially proposed in PEP 518 and later expanded in PEP 517, PEP 621 and PEP 660, which made it is possible to make a package without the use of any setup script or external packages.

Would be really nice to have dependabot detect those dependencies and open pull requests to keep them up to date :)

References:

• Documentation for pip on pyproject.toml: https://pip.pypa.io/en/stable/reference/build-system/pyproject-toml/
• Example of pyproject.toml only package: https://github.com/FasterSpeeding/Tanjun/blob/master/pyproject.toml

[choldgraf]

Just a note that this would be useful for us as well. I am seeing more and more Python projects migrating from the setuptools workflow to one that uses pyproject.toml, especially now that projects like flit support editable installs (with pip install -e). It feels like pyproject.toml is the future standard for Python library dependency configuration, and I'd really appreciate supporting this feature in dependabot.

[rouge8]

I think this is a duplicate of #3290

[davfsa]

Seems to be so, will close then :)