Bug#1086333: OpenSlide Python 1.4.0 released

[Benjamin Gilbert]

Package: python3-openslide
Version: 1.3.1-2

OpenSlide Python 1.4.0 has been released.  Because setuptools 69.3+
normalizes package names in sdist tarballs to conform to PEP 625, the
OpenSlide Python source tarball is now called openslide_python-*, so
debian/watch will not automatically notice the new release.