first set up of pyprojetc.toml and corresponding action

[DKreuter]

This pull request makes several important updates to the package's build system, packaging configuration, and documentation. The main focus is migrating from legacy setup.cfg/setup.py configuration to a modern, PEP 621-compliant pyproject.toml-based setup, as well as improving the CI workflow for building and publishing the package. Additionally, there are minor docstring and code style improvements in the DeepONet data loader.

Build system and packaging modernization:

• Migrated all project metadata and configuration from setup.cfg to pyproject.toml, adopting the PEP 621 standard for specifying project metadata, dependencies, optional dependencies, and build system requirements. This simplifies and modernizes the package configuration. [1] [2]
• Simplified setup.py to a minimal file that just calls setuptools.setup(), removing PyScaffold-specific logic and error handling.

Continuous Integration and Deployment improvements:

• Overhauled the GitHub Actions workflow in .github/workflows/pypi-deploy.yml:
  • Added build and test triggers for ci-debug, master, and develop branches.
  • Enabled building wheels for both Ubuntu and Windows, using cibuildwheel.
  • Updated build matrix to support Python 3.9–3.13.
  • Switched sdist building to use python -m build.
  • Improved PyPI publishing steps, including support for Trusted Publishing and test PyPI uploads for non-release events. [1] [2] [3]

Code and documentation improvements:

• Improved docstrings and code style in src/torchphysics/utils/data/deeponet_dataloader.py for clarity, formatting, and minor typo corrections. [1] [2] [3] [4] [5] [6] [7]

These changes collectively modernize the project's packaging and deployment, improve cross-platform support, and enhance code readability and maintainability.