Remove pkg_resources as a dependency

[FelipeGdM]

The pkg_resources module from setuptools have been deprecated and removed in python 3.12. It's still possible to use it downgrading setuptools to version 81.0.0, but a long term solution would be to replace it entirely

In this context, the goal of this PR is to replace the use of the pkg_resources along SAPIEN source code

In order to accomplish this gaol, the recommended alternatives are importlib.resources, importlib.metadata and their backports (importlib_resources, importlib_metadata)

The importlib.resources library provides a useful migration guide in order to move away from pkg_resources, so the implementation is pretty straightforward

As SAPIEN aims to support python 3.8, it's also needed to perform a conditional import, as importlib.resources is only available for python 3.9 or newer