Update the code to be compatible with the vtk version 9.6

The new version 9.6 of vtk introduces changes for some classes with deprecated functions (leading to warnings for now) and update other classes to add functions or metrics (leading to error for qc functions).

This update may be done once ParaView will deal with vtk 6.9, otherwise, the ParaView plugins implemented in geos-pv will not work. 