Update debian/watch to use github instead of pypi.

The github tarball contains the documentation files we need to
generate the docs for Debian, whereas the pypi tarball is stripped of
the .rst files.

debian/watch

@@ -1,3 +1,4 @@
-version=3
-
-https://pypi.python.org/packages/source/k/kitchen/kitchen-(.+).tar.gz
+version=4
+opts="filenamemangle=s%(?:.*?)?v?(\d[\d.]*)\.tar\.gz%kitchen-$1.tar.gz%" \
+   https://github.com/fedora-infra/kitchen/releases \
+   (?:.*?/)?v?(\d[\d.]*)\.tar\.gz debian uupdate