update slot resume pointers for step 8300

slots/12/latest.json

@@ -1 +1 @@
-{"worker_id": "slot:12", "checkpoint": "slots/12/checkpoint-7732", "step": 7732, "updated_at": 1776773901}
+{"worker_id": "slot:12", "checkpoint": "slots/12/checkpoint-8300", "step": 8300, "updated_at": 1776776108}