update slot resume pointers for step 502

slots/7/latest.json

@@ -1 +1 @@
-{"worker_id": "slot:7", "checkpoint": "slots/7/checkpoint-376", "step": 376, "updated_at": 1776358747}
+{"worker_id": "slot:7", "checkpoint": "slots/7/checkpoint-502", "step": 502, "updated_at": 1776388577}