update build system

[nbdy]

Fixes

...
      ModuleNotFoundError: No module named 'pkg_resources'
      hint: This error likely indicates that `vunit-hdl@4.7.0` depends on
      `pkg_resources`, but doesn't declare it as a build dependency. If
      `vunit-hdl` is a first-party package, consider adding `pkg_resources`
      to its `build-system.requires`. Otherwise, either add it to your
      `pyproject.toml` under:
      [tool.uv.extra-build-dependencies]
      vunit-hdl = ["pkg_resources"]
      or `uv pip install pkg_resources` into the environment and re-run with
      `--no-build-isolation`.
...

The previous setup.py relied on a legacy setuptools environment where pkg_resources was assumed to be available. In modern, slim CI environments using uv, build isolation often lacks this deprecated module, leading to the ModuleNotFoundError. Transitioning to pyproject.toml with hatchling eliminates this legacy dependency and explicitly defines the build requirements, ensuring compatibility with modern Python packaging standards.

[Trooper-X]

Relates to: #1158

[nbdy]

With the original change the python files were not included in the build by hatchling, which i just noticed.
This is fixed with the latest commit.