I actually began (and finished) work on packaging python-xxhash before
noticing this ITP. My initial packaging is at:
https://github.com/rfinnie/python-xxhash-pkg-debian
Since libxxhash0 was recently packaged, I've patched the Python module
to use the shared library instead of the module's local copy. Aside
from that, relatively normal Python module. The module itself is Python
2.7 compatible but I only packaged Python 3, per lintian
new-package-should-not-package-python2-module.
Feel free to use this packaging base if you want and set yourself as the
maintainer. I'd also be happy with being the maintainer (I'm a DM, not
a DD so I would require an initial sponsorship as DMs aren't allowed to
upload new packages), your choice.