DeprecationWarning: tostring() is deprecated. Use tobytes() instead.

Running create-init_CMIP6-OMIP_Salinity.py gives the following warning at three locations: lines 115, 130, 138

DeprecationWarning: tostring() is deprecated. Use tobytes() instead.

Doesn't hinder the process - but would be nice not to appear (something to do with py3 vs. py2 - I assume)