Switch to pyproject.toml

[Copilot]

I took the bot changes, made them actually work, and also

• Switched to setuptools_scm, which has the benefits of
  • Not being vendored code that easily falls out of date
  • Does not require the full git history
  • Works for me locally
• Added pyproject-fmt linter
• Updated the docstring of get_forcefield_dirs_paths

Bot text below the line

Consolidates all Python packaging and tooling config into pyproject.toml, removing setup.py, setup.cfg, and MANIFEST.in.

Description

• [build-system] — setuptools + versioneer[toml]
• [project] — metadata (name, description, authors, license, readme, entry points, package data) migrated from setup.py
• [tool.versioneer] — moved from [versioneer] in setup.cfg
• [tool.coverage.run] — moved from [coverage:run] in setup.cfg
• Deleted: setup.py, setup.cfg, MANIFEST.in

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (ef71ca2) to head (8e723ba).

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.