Function get_python_package_version_opt 

pub fn get_python_package_version_opt(package_name: &str) -> Option<String>

Returns the __version__ of a Python package, or None when it is not installed (or does not expose a usable __version__).

Unlike get_python_package_version, this distinguishes “not installed” from a real version so callers can omit absent packages instead of logging an “Unavailable” line.