Remove using `pkg_resources` package

Usage of pkg_resources is deprecated, and no longer installed (by default) in python 3.12 (it's merged into setuptools). This causes problems when running g4camp on python >3.11

We have options:

1. Use importlib.resources as a drop-in replacement
2. Add setuptools to dependencies
3. We actually don't need the pkg_resources - it's used in lines https://git.jinr.ru/malyshkin/g4camp/-/blob/main/g4camp/g4camp.py#L5 just to check if the geant4-pybind can be imported. Why not use try-catch instead:

try:
    from geant4_pybind import *
except:
    sys.exit("Package 'geant4_pybind' is not available.")

I think the option 3 is the cleanest solution.