Logs are cluttered with FutureWarnings for ebooklib package

[rhigman]

In every run, the following warning is raised, sometimes multiple times:

/usr/local/lib/python3.11/site-packages/ebooklib/epub.py:1410: FutureWarning: This search incorrectly ignores the root element, and will be fixed in a future version.  If you rely on the current behaviour, change it to './/xmlns:rootfile[@media-type]'
  for root_file in tree.findall('//xmlns:rootfile[@media-type]', namespaces={'xmlns': NAMESPACES['CONTAINERNS']}):

Unfortunately this is due to a bug in the ebooklib package, which hasn't yet been fixed in a released version: aerkalov/ebooklib#307

Once a release with the fix is made, we should upgrade the dependency.