Fix flashinfer >= 0.0.3 compat (#282)

python/sglang/srt/managers/router/model_runner.py

 import importlib
 import logging
+import inspect
 from dataclasses import dataclass
 from functools import lru_cache
 from pathlib import Path
@@ -124,14 +125,21 @@ class InputMetadata:
             self.prefill_wrapper = BatchPrefillWithPagedKVCacheWrapper(
                 workspace_buffer, "NHD"
             )
-            self.prefill_wrapper.begin_forward(
+            args = [
                 self.qo_indptr,
                 self.kv_indptr,
                 self.kv_indices,
                 self.kv_last_page_len,
                 self.model_runner.model_config.num_attention_heads // tp_size,
                 self.model_runner.model_config.num_key_value_heads // tp_size,
-            )
+            ]
+
+            # flashinfer >= 0.0.3
+            # FIXME: Drop this when flashinfer updates to 0.0.4
+            if len(inspect.signature(self.prefill_wrapper.begin_forward).parameters) == 7:
+                args.append(self.model_runner.model_config.head_dim)
+            
+            self.prefill_wrapper.begin_forward(*args)
         else:
             self.decode_wrapper = BatchDecodeWithPagedKVCacheWrapper(
                 workspace_buffer, "NHD"