[revert] remove version set for PythonLibs.

cmake/modules/DunePythonCommonMacros.cmake

@@ -77,11 +77,6 @@ set(Python_ADDITIONAL_VERSIONS 3.8 3.7 3.6 3.5 3.4)
 # Find the Python Interpreter
 find_package(PythonInterp 3)
 
-# interpreter was found set available version of library to that version
-if(PYTHONINTERP_FOUND)
-  set(Python_ADDITIONAL_VERSIONS ${PYTHON_VERSION_MAJOR}.${PYTHON_VERSION_MINOR})
-endif()
-
 # Find the Python libraries
 find_package(PythonLibs)