OpenSlide binary build 4.0.0.6 released

[Benjamin Gilbert]

Hi all,

OpenSlide binary build 4.0.0.6 has been released, switching from zlib
to zlib-ng and updating various dependencies.  For the full changelog,
see below.

openslide-bin 4.0.0.6 is available for download under the terms of the
GNU Lesser General Public License, version 2.1:

    https://openslide.org/download/#binaries

Thanks,
--Benjamin Gilbert

===

* Switch from zlib to zlib-ng
* Export type hints from Python package
* Reduce size of source archive
* Update various dependencies