Unnecessary VTK API change

[banesullivan]

@mwestphal

One of note from pyvista (@banesullivan ):

We wouldn’t blame you for being ruthlessly annoyed by the continual deprecation churn from Vtk. We kinda are. Like, seriously. Vtk, can you just slow down that moving API target a little there? face_exhaling

I want to clarify that I wasn’t the one who said that… Originally posted here: vtkThreshold::ThresholdByUpper was deprecated for VTK 9.1 and will be removed in a future version. · Issue #2850 · pyvista/pyvista · GitHub

@mwestphal

That being said, this should have been caught much earlier imo in order to avoid forcing VTK users to change their use of VTK.

Agreed!