play gifs when hovering over notification

src/components/notification/notification.scss

@@ -4,6 +4,12 @@
 .Notification {
   --emoji-size: 14px;
 
+  &:hover {
+    --_still-image-img-visibility: visible;
+    --_still-image-canvas-visibility: hidden;
+    --_still-image-label-visibility: hidden;
+  }
+
   &.-muted {
     padding: 0.25em 0.6em;
     height: 1.2em;