Update to pyproject.toml

[braceal]

Seeing this warning when I install via pip install -e .

 DEPRECATION: Legacy editable install of mdlearn[torch]==0.0.10a1 from file:///Users/abrace/projects/ddwe/src/mdlearn
 (setup.py develop) is deprecated. pip 25.0 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 https://github.com/pypa/pip/issues/11457