Fix to https://huggingface.co/tiny-random/glm-5/discussions/1

Set `index_head_dim` to 128 as in the original model config https://huggingface.co/zai-org/GLM-5/blob/main/config.json#L18

config.json

@@ -16,7 +16,7 @@
   "head_dim": 64,
   "hidden_act": "silu",
   "hidden_size": 8,
-  "index_head_dim": 32,
+  "index_head_dim": 128,
   "index_n_heads": 4,
   "index_topk": 2048,
   "indexer_rope_interleave": true,