Update CMakeLists.txt for recent VTK to fix CMake Warning

[janetournois]

Summary of Changes

Versions >= 9 of VTK trigger the following CMake warning using CGAL's CMakeLists

CMake Deprecation Warning at C:/dev/VTK-9.2.2/build/lib/cmake/vtk-9.2/vtk-use-file-deprecated.cmake:1 (message):
  The `VTK_USE_FILE` is no longer used starting with 8.90.
Call Stack (most recent call first):
  CMakeLists.txt:32 (include)

I suggest this modification of the CMakeLists of Mesh_3 examples, that also requires moving to VTK 9 (9.0 was released in 2020). If this modification and new requirement are validated, I can apply the change everywhere.

Release Management

• Affected package(s): Mesh_3 for now
• License and copyright ownership: unchanged

[sloriot]

Successfully tested in CGAL-6.0-Ic-265