Bug#975004: python3-paraview: ships vtk modules which are also packaged by python3-vtk9

[Drew Parsons]

I got this error reporting the file clash between python3-vtk9 and 
python3-paraview 5.7 during upgrade on unstable from the vtk-7 versions.

I think it means python3-vtk9 needs the break/replaces as well. Should 
show up in piuparts reports.