Fix serializing DeleteSegmentDataUpdateAction (#8362)

Author: fm3

webknossos-tracingstore/app/com/scalableminds/webknossos/tracingstore/annotation/UpdateActions.scala

@@ -165,6 +165,8 @@ object UpdateAction {
         Json.obj("name" -> "updateSegment", "value" -> Json.toJson(s)(UpdateSegmentVolumeAction.jsonFormat))
       case s: DeleteSegmentVolumeAction =>
         Json.obj("name" -> "deleteSegment", "value" -> Json.toJson(s)(DeleteSegmentVolumeAction.jsonFormat))
+      case s: DeleteSegmentDataVolumeAction =>
+        Json.obj("name" -> "deleteSegmentData", "value" -> Json.toJson(s)(DeleteSegmentDataVolumeAction.jsonFormat))
       case s: UpdateSegmentGroupsVolumeAction =>
         Json.obj("name" -> "updateSegmentGroups", "value" -> Json.toJson(s)(UpdateSegmentGroupsVolumeAction.jsonFormat))
       case s: UpdateMappingNameVolumeAction =>