Bug#981378: paraview: segfaults at startup via libvtkCommonCore-pv5.9.so

[Drew Parsons]

Package: meshio-tools
Followup-For: Bug #981378
Control: severity -1 important
Control: forwarded -1 https://gitlab.kitware.com/paraview/paraview/-/issues/20412

Probably severity grave is overegging it.
paraview and meshio-tools won't necessarily be installed at the same
time. paraview will work fine if meshio-tools is not installed.
The meshio-tools themselves (apart from the plugin) work fine.

Downgrade severity to important.