COMP: Update to newer find_package(Python3) support

The Python3 cmake find_package module was first added in version 3.12
This module provides more rigorous support for specifying
the exact version and components that are needed.  The module
has refinements in newer cmake versions to limit the
version and specify the ABI required.

Author: hjmjohnson

CMake/vtkMacroKitPythonWrap.cmake

@@ -160,7 +160,7 @@ macro(vtkMacroKitPythonWrap)
 
   if(VTK_WRAP_PYTHON AND BUILD_SHARED_LIBS)
 
-    # Tell vtkWrapPython.cmake to set VTK_PYTHON_LIBRARIES for us.
+    # Tell vtkWrapPython.cmake to set VTK_Python3_LIBRARIES for us.
     set(VTK_WRAP_PYTHON_FIND_LIBS 1)
     include(vtkWrapPython)
 
@@ -283,7 +283,7 @@ macro(vtkMacroKitPythonWrap)
       ${MY_KIT_NAME}PythonD
       ${MY_KIT_NAME}
       ${VTK_PYTHON_CORE}
-      ${VTK_PYTHON_LIBRARIES}
+      ${VTK_Python3_LIBRARIES}
       ${VTK_KIT_PYTHON_LIBRARIES}
       ${MY_KIT_PYTHON_LIBRARIES}
       )
@@ -344,7 +344,7 @@ macro(vtkMacroKitPythonWrap)
     target_link_libraries(${MY_KIT_NAME}Python
       PRIVATE
         ${MY_KIT_NAME}
-        ${VTK_PYTHON_LIBRARIES}
+        ${VTK_Python3_LIBRARIES}
         VTK::WrappingPythonCore
         VTK::Python
         )

CMake/vtkWrapPython.cmake

@@ -189,14 +189,14 @@ if(VTK_WRAP_PYTHON_FIND_LIBS)
   else()
     set(_QUIET_LIBRARY "REQUIRED")
   endif()
-  find_package(PythonLibs ${_QUIET_LIBRARY})
+  find_package(Python3 COMPONENTS Development ${_QUIET_LIBRARY})
 
   # Use separate debug/optimized libraries if they are different.
   if(PYTHON_DEBUG_LIBRARY)
     if("${PYTHON_DEBUG_LIBRARY}" STREQUAL "${PYTHON_LIBRARY}")
-      set(VTK_PYTHON_LIBRARIES ${PYTHON_LIBRARY})
+      set(VTK_Python3_LIBRARIES ${PYTHON_LIBRARY})
     else()
-      set(VTK_PYTHON_LIBRARIES
+      set(VTK_Python3_LIBRARIES
         optimized ${PYTHON_LIBRARY}
         debug ${PYTHON_DEBUG_LIBRARY})
     endif()
@@ -207,7 +207,7 @@ if(VTK_WRAP_PYTHON_FIND_LIBS)
       endif()
     endif()
   else()
-    set(VTK_PYTHON_LIBRARIES ${PYTHON_LIBRARY})
+    set(VTK_Python3_LIBRARIES ${PYTHON_LIBRARY})
   endif()
 
   # Some python installations on UNIX need to link to extra libraries
@@ -224,7 +224,7 @@ if(VTK_WRAP_PYTHON_FIND_LIBS)
   endif()
 
   # Include any extra libraries for python.
-  set(VTK_PYTHON_LIBRARIES ${VTK_PYTHON_LIBRARIES} ${PYTHON_EXTRA_LIBS})
+  set(VTK_Python3_LIBRARIES ${VTK_Python3_LIBRARIES} ${PYTHON_EXTRA_LIBS})
 endif()
 
 # Determine the location of the supplied header in the include_dirs supplied.