Package: Use standard `setuptools` or `uv` build backend

[amotl]

It looks like Hatch is needed to build this project now, but that isn't mentioned in DEVELOP.rst - the whole file looks sort of outdated, together with the bootstrap.sh.

Can we simplify that, so there's some sort of standard uv venv venv; uv pip install -Ue ".[dev]" with no special custom logic?

Originally posted by @mfussenegger in #759 (comment)

[amotl]

I like to use versioningit like introduced per GH-757, but the uv build backend does not support it yet (astral-sh/uv#14137), so my vote is to use the standard setuptools build backend. I think this doesn't prevent using the project with uv and hatch utilities, does it?

[amotl]

build backend: setuptools vs. hatchling

@surister probably wanted to bring in benefits like outlined in Why Hatch?. I am a happy setuptools user, but didn't want to stop any progress here. Hatch seems to be used on other projects, so I don't have any objections against it, but I would also not object against switching back to setuptools. Please advise.