- Update to 3.0.0
* The serialization API has been reworked. Instead of consuming a serializer
and deserializer as separate arguments, client objects now expect an argument
``serde`` to be an object which implements ``serialize`` and ``deserialize``
as methods. (``serialize`` and ``deserialize`` are still supported but
considered deprecated.)
* Validate integer inputs for ``expire``, ``delay``, ``incr``, ``decr``, and
``memlimit`` -- non-integer values now raise ``MemcacheIllegalInputError``
* Validate inputs for ``cas`` -- values which are not integers or strings of
0-9 now raise ``MemcacheIllegalInputError``
* Add ``prepend`` and ``append`` support to ``MockMemcacheClient``.
* Add the ``touch`` method to ``HashClient``.
* Added official support for Python 3.8.