Remove the shutdown notice.

Summary:
According to https://blog.libravatar.org/posts/Libravatar.org_is_not_going_away/,
libravatar didn't (and won't) go away.

Reviewers: mlaurent

Reviewed By: mlaurent

Subscribers: kde-pim

Tags: #kde_pim

Differential Revision: https://phabricator.kde.org/D16892