The tag is present in Lintian version 2.104.232. That is the most recent version we know about.
The specified email address uses lists.alioth.debian.org. That system was migrated to a separate debian.net system run by DDs. Teams were encouraged to migrate to the new system, but they are also free to use the old address going forward if they like.
For further information, please consult the Debian Wiki.
Refer to https://wiki.debian.org/Alioth/MailingListContinuation and Bug#962448 for details.
This is a classification. There is no issue with your package.