update Pipfile.lock
update Pipfile.lock

hopefully solves security warning for "requests"
which is pulled in via the sphinx dependency

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