New issue by kwshi on void-packages repository

https://github.com/void-linux/void-packages/issues/30551

Description:
Purpose: Support Python packages built using Poetry (via PEP 517).

The Python community is moving increasingly towards [Poetry](https://python-poetry.org/) as a de-facto project management/build tool (I have no stats to back this claim up, only speculation based on an increasing number of blog posts I have seen about Poetry, as well as my own pleasant experiences with it).  Together with [PEP 517](https://www.python.org/dev/peps/pep-0517/), this trend means that

- several existing Python packages are migrating from `setup.py`-based builds to PEP517+Poetry builds (e.g., see #29799),
- new Python projects are likely to be created from scratch using Poetry (and therefore built using Poetry as well).

As far as I can tell, the existing Void packages repo does not yet support Poetry-based builds.  The _infrastructure_ is already in place: PEP517 build configurations are supported via `build_style="python3-pep517"`; the missing part is the Poetry _builder_ itself, namely [`poetry-core`](https://github.com/python-poetry/poetry-core), which is loaded by the PEP517 build runner when a project specifies Poetry as the build backend ([example](https://github.com/sdispater/tomlkit/blob/d34a1fe7494aac74e1f0ccdb993c4ee2f8e4f305/pyproject.toml#L67-L69)) and therefore needs to be present as a build-time dependency.

That means the only thing that needs to be done to support (a vast & popular collection of, and likely even more so in the coming years) Poetry-based Python packages is to add the `poetry-core` Python package.

Note that `poetry-core` is _not_ the same as the [Poetry CLI](https://github.com/python-poetry/poetry/), which is an interactive/user-friendly frontend to managing Poetry-based projects.  [Only `poetry-core`, which is a lightweight, zero-dependency library, _not_ the CLI, is needed for building via PEP517.](https://github.com/python-poetry/poetry-core#why-is-this-required)