Modernise build tooling and configuration

[MarkBird]

Transition the project from the old-school setup.py style to the more modern pyproject.toml approach.

[dabapps-robot]

Nice modernisation overall 👍 — moving to pyproject.toml, switching to python -m build, and using pypa/gh-action-pypi-publish is a solid improvement and simplifies release management a lot.

A couple of things worth checking before merge:

1. Potential compatibility mismatch (requires-python vs build backend constraint)
   In pyproject.toml, runtime support is declared as >=3.8, but build requires setuptools>=77.0.0.
   It’d be worth confirming that this setuptools floor is compatible with your stated Python support window. If not, you may want to lower the minimum setuptools version to one that still supports Python 3.8.

2. __version__ removal from package namespace
   log_request_id.__version__ has been removed from __init__.py. If any consumers read that attribute directly, this is a small API break.
   If backward compatibility matters, consider keeping __version__ (even if canonical versioning now lives in pyproject.toml).

If those are intentional/confirmed, this looks good to merge from my side.

[MarkBird]

Closing to redo with latest Django/Python versions