Syw UID2 6085 improve python dependency

[sunnywu]

1. Python Version & Dependency Updates

• Minimum Python Version Raised: The required Python version was updated from >=3.6 to >=3.10. This change was necessary because the code uses importlib.metadata, which was introduced in Python 3.8, fixing import errors on older versions.
• Version Support Modified: Classifiers were updated to remove support for end-of-life Python 3.6-3.9, while explicitly adding support for Python 3.10+
• Dependency Constraint Relaxed: The version constraint for setuptools was relaxed from a fixed version (== 68.2.2) to a broader range (< 81), increasing flexibility while maintaining compatibility.

2. Modernizing Package Configuration

• Removed Legacy Files: The legacy Python packaging files, setup.py and setup.cfg, were removed.
• Adopted pyproject.toml: The pyproject.toml file was updated to configure proper package discovery, marking a shift to a modern Python packaging standard.
• Build Fixes: Fixed a Docker build error caused by multiple top-level packages and updated Dockerfile.dev to use a Python 3.10 base image.
• Excluded Directories: Directories like node_modules, tests, examples, and venv are now explicitly excluded from package discovery.

3. CI and Testing Enhancements

• Unit Tests Added to CI: A new unit-tests job was added to the Continuous Integration workflow (build-and-test.yaml).
• Pre-Publish Test Gate: A dependency was added to the build-and-publish workflow to ensure unit tests pass before publishing to PyPI, preventing broken code from being released.
• Development Dependencies Updated: Development dependencies (e.g., pytest, pytest-cov, unittest-xml-reporting) were added to pyproject.toml.
• Test Confirmation: The developer confirmed locally that 287 tests pass successfully with these changes.

[cYKatherine]

why do we use matrix here 🤔

[sunnywu]

so we could define a range of setups to run unit tests on, e.g. like below i extended to not just run unit tests on py 3.8 but 3.9/3.10/etc add test coverage, like this run:

https://github.com/IABTechLab/uid2-client-python/actions/runs/18513552871