Wrap up python 3 based version

This ece2cmor3 v2.0.1 release is a wrap up of the first python3 based version (#748).

A few last changes have been addressed to make ece2cmor3 v2.0.1 the fully validated release after the trnasition from python 2.7.15 to python 3.11.0. Beside wrap up / clean changes now we are over, the main change is that Ofx basin is set equal to its previous state, for details see #754. Further all deprecation warnings at the ece2cmor3 side have been resolved #757.