The Italian Dictionary Add-ons can not be install

The Italian Dictionary Add-ons (https://trisquel.info/en/browser/addons/italian-dictionary) can not be install.

For now I fixed it downloading the old version (3.3.2) here:
(https://addons.mozilla.org/en-US/firefox/addon/dizionario-italiano/versions/?page=1#version-3.4.0).
Abrowser update at the last version (3.4.0) without problem.