gh-90494: Reject 6th element of the __reduce__() tuple (GH-93609) (GH-93631)

copy.copy() and copy.deepcopy() now always raise a TypeError if
__reduce__() returns a tuple with length 6 instead of silently ignore
the 6th item or produce incorrect result.
(cherry picked from commit a365dd64c2a1f0d142540d5031003f24986f489f)

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