MITK requires python 3, so we should use the new FindPython3:
Also, FindPython3 should probably be called in the associated Config.cmake
Why currently in top level CmakeLists.txt and also other places associated with the new MITK python wrapping? And why is the config file called MITK_PythonLibs_Config.cmake and now, corresponding to the variable MITK_Python_Config.cmake?
Required cmake version will be upgraded to 3.12 in T25420