Promote package from beta to stable by updating version strings from 5.0.0b5 to 5.0.0 in pyproject.toml and ytsage/__init__.py. Prepares the project for the 5.0.0 release.
Replaced requirements.txt with pyproject.toml to modernize project configuration and dependency management using PEP 621 standards. This change improves compatibility with modern Python packaging tools.