fix draft cuda graph capture failure (#3431)

python/sglang/srt/speculative/eagle_draft_cuda_graph_runner.py

@@ -85,6 +85,7 @@ class EAGLEDraftCudaGraphRunner:
                 "1. disable cuda graph by --disable-cuda-graph\n"
                 "2. set --mem-fraction-static to a smaller value (e.g., 0.8 or 0.7)\n"
                 "3. disable torch compile by not using --enable-torch-compile\n"
+                "4. specify --dtype to the same dtype (e.g. bfloat16)\n"
                 "Open an issue on GitHub https://github.com/sgl-project/sglang/issues/new/choose \n"
             )