use get_latest() instead of _latest() for #393
use get_latest() instead of _latest() for #393

Related to QCoDeS update

DiCarloLab-Delft/PycQED_py3,QudevETH/PycQED_py3,DiCarloLab-Delft/PycQED_py3,DiCarloLab-Delft/PycQED_py3