x11-fm/dolphin: update to 21.12.2.1
- This includes a minor change in the service url lookup to use the KDE CDN. https://invent.kde.org/system/dolphin/-/commit/d0898592a17d14fc8d48fc5cba71f3d57f0a1856
(cherry picked from commit 24bb183c9ca4f140e6c14f42c4161e107cf6d51b)