[guix] Don't install Python in lib-dir.

Follow-up on
ogs/ogs@48a89587

scripts/cmake/packaging/Pack.cmake

@@ -75,7 +75,7 @@ if(WIN32)
     file(COPY ${PYTHON_RUNTIME_LIBS}
          DESTINATION ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}
     )
-else()
+elseif(NOT GUIX_BUILD)
     install(FILES ${Python_LIBRARIES} DESTINATION ${CMAKE_INSTALL_LIBDIR})
 endif()