Chore: modern build

[ushiboy]

Summary

Migrate from setup.py to modern pyproject.toml-based build system and update development dependencies to use latest versions on Python 3.10+.

Changes

Build System Migration

• pyproject.toml: Created modern PEP 518/621 compliant configuration
  • SPDX-style license declaration
  • Setuptools backend with metadata
• setup.py: Simplified to minimal compatibility wrapper
• Build command: python setup.py sdist bdist_wheel → python -m build

Development Dependencies (develop-requirements.txt)

Updated to use latest tool versions on Python 3.10+ while maintaining compatibility with Python 3.7-3.9:

GitHub Actions Workflow

• Added build test step for Python 3.10+
• Condition: Skip build on Python 3.7, 3.8, 3.9 only

Build Policy

• Distribution packages (sdist/wheel) must be built using Python 3.10 or higher
• Python 3.7-3.9 remain supported for development and testing
• Build tools (build, wheel, twine) only installed on Python 3.10+