[3.14] gh-78465: Fix error message for cls.__new__(cls, ...) where cls is not instant...

[3.14] gh-78465: Fix error message for cls.__new__(cls, ...) where cls is not instantiable (GH-135981) (GH-136030)

Previous error message suggested to use cls.__new__(), which
obviously does not work. Now the error message is the same as for
cls(...).
(cherry picked from commit c45f4f3ebe34529a8db3a7918e8dd2e9f7ce8e86)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>