serialization/support: corrected SerSequence serialize();¹ tidy.
serialization/support: corrected SerSequence serialize();¹ tidy.

1: Unused template type parameter `class S` was (rightfully)
causing deduction failure in has_serializer_serialize<Ser, T>.
Also, serialize() cannot take rvalue ref due to no uniform
forwarding, so it now takes lvalue ref.

komiga/togo,komiga/togo,komiga/togo