Support PEP 621 in Poetry 2.0+

[mkniewallner]

Is your feature request related to a problem? Please describe.

Poetry 2.0 now supports defining project metadata using PEP 621 format.

Currently, we assume that a project uses Poetry if we find a [tool.poetry] section in pyproject.toml. Once found, we only look for dependencies under [tool.poetry.dependencies], [tool.poetry.dev-dependencies] and [tool.poetry.group.<group>.dependencies].

The assumptions we do are not correct anymore, as projects using Poetry can have a [tool.poetry] section for Poetry specific metadata, while having their dependencies in dependencies under [project].

Besides, even with the new format, it is still possible to define dependencies under [tool.poetry.dependencies], either to fully define dependencies, or enrich dependencies under [project] with some additional information.

Describe the solution you would like

Need to dig more into that, but a possible solution would be to:

• make PoetryDependencyGetter extends PEP621DependencyGetter
• continue assuming that Poetry is used if we detect a [tool.poetry] section
  • if the section is not present but the project uses Poetry, this means that it doesn't use any Poetry-specific sections for defining dependencies
• enrich PEP 621 dependencies with Poetry-specific ways of defining dependencies, similarly to what we do for uv and PDM

Additional context

Dependency groups (PEP 735) are not supported, but we can assume that since this is not supported by Poetry, people using Poetry would not populate those sections (like we did for PDM at the time before it added support for it).