modernize doc/conf.py
modernize doc/conf.py

robertodr/xcfun,bast/xcfun,bast/xcfun,dftlibs/xcfun,dftlibs/xcfun,robertodr/xcfun,bast/xcfun,robertodr/xcfun,dftlibs/xcfun,bast/xcfun,dftlibs/xcfun,robertodr/xcfun