Migrate from `setup.py` to `pyproject.toml`

[namurphy]

Description

I propose migrating dbprocessing from setup.py to pyproject.toml for the package configuration.

It's likely that this would require dropping support for Python 2.7 in future releases of dbprocessing.

Motivation

The pythoniverse has largely moved away from using setup.py, and compatibility with modern tools like uv require having a pyproject.toml.

Switching to pyproject.toml would enable usage of modern Python packaging features such as dependency groups. Using dependency groups lets the project define dependencies needed to build documentation and run tests, for examples, without making these dependencies available to end users like optional dependencies do.

It's also possible to use tools like validate-pyproject to identify errors in project configurations.

Note

Using uv in CI is helpful in many ways, including by running tests against the minimum allowed versions of direct dependencies (with their --lowest-direct resolution strategy).

Closure condition

This issue should be closed when pyproject.toml has replaced setup.py, and all tests are run successfully with setup.py.

Thank you for creating what looks like a really useful package!

[jtniehof]

Agreed, this is a simple pure-Python package. The only fanciness I was doing in setup.py is to auto-build the docs before building the source package, and I think we can get around that.

Would help with #141.

Also I'm good with dropping 2.7 support basically now. Trying to get the CI working properly with that is part of the holdup on #137 (that and graduation :) )