Remove unused import

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: github-actions[bot]

experiments/grug/moe/great_10t_first_k_dense.py

@@ -13,7 +13,6 @@
 """
 
 import math
-from dataclasses import replace
 
 from fray.cluster import ResourceConfig
 from levanter.optim import AdamConfig