update slot resume pointers for step 1668

slots/3/latest.json

@@ -1 +1 @@
-{"worker_id": "slot:3", "checkpoint": "slots/3/checkpoint-643", "step": 643, "updated_at": 1776397607}
+{"worker_id": "slot:3", "checkpoint": "slots/3/checkpoint-1668", "step": 1668, "updated_at": 1776404676}