vtkVersion: update to the 9.3 release series

CMake/vtkVersion.cmake

 # VTK version number components.
 set(VTK_MAJOR_VERSION 9)
-set(VTK_MINOR_VERSION 2)
+set(VTK_MINOR_VERSION 3)
 set(VTK_BUILD_VERSION 20230807)
 
 if (NOT VTK_MINOR_VERSION LESS 100)