Move to using pyproject.toml to ensure compatibility after pip 25.3

[thvasilo]

pip is going to disallow editable installs for projects that use setup.py from pip 25.3. See discussion in pypa/pip#11457

Currently, installing graphstorm from source with pip install -e ./graphstorm gives the warning:

DEPRECATION: Legacy editable install of graphstorm==0.5.0 from file:///home/ec2-user/SageMaker/graphstorm (setup.py develop) is deprecated. pip 25.3 will enforce this behaviour change. A possible replacement is to add a pyproject.toml or enable --use-pep517, and use setuptools >= 64. If the resulting installation is not behaving as expected, try using --config-settings editable_mode=compat. Please consult the setuptools documentation for more information. Discussion can be found at pypa/pip#11457

setup.py has been on the path of deprecation for a while, we should adopt the modern pyproject.toml to ensure forward compatibility of the library.