Consider renaming manifest key pypi-dependencies

[Hofer-Julian]

Problem description

I feel like the name pypi-dependencies is pretty confusing: https://pixi.sh/dev/reference/configuration/#pypi-dependencies-beta-feature

Naming it after PyPI implies to me that the packages come from https://pypi.org/, but that isn't necessarily the case.
I liked pip-dependencies but @tdejager told me that isn't exactly an improvement.
What is happening is that you either install a binary or source distribution. Maybe whl-sdist-dependencies would work?

[ruben-arts]

The though was:
python-dependencies is unfair as conda packages can contain python packages.
py-dependencies insists previous option.

We looked into what a convention would be but nothing specifies a different word for a python package.

pip-dependencies is equally weird as it makes the user think it is installed by pip.

There are a few server options that take over the pypi name to so we decided to make everything in the whole code-base pypi.

I don't see a good reason to do a change at the moment. Feel free to share some cases where users are confused or think they have a better option.

I'm moving this to a discussion as I understand we should have an open discussion but it doesn't fit in the issues.