refactor deepseek_ocr/fun_asr_nano generate code

tests/test_deepseek_ocr.rs

@@ -127,10 +127,6 @@ async fn deepseek_ocr_stream() -> Result<()> {
                     }
                 ]
             },
-            {
-                "role": "assistant",
-                "content": ""
-            }
         ],
         "metadata": {"base_size": "640", "image_size": "640", "crop_mode": "false"}
     }

tests/test_fun_asr_nano.rs

@@ -54,7 +54,7 @@ fn fun_asr_nano_generate() -> Result<()> {
 
 #[tokio::test]
 async fn fun_asr_nano_stream() -> Result<()> {
-    // RUST_BACKTRACE=1 cargo test -F cuda fun_asr_nano_stream -r -- --nocapture
+    // RUST_BACKTRACE=1 cargo test -F cuda --test test_fun_asr_nano fun_asr_nano_stream -r -- --nocapture
     let save_dir =
         aha::utils::get_default_save_dir().ok_or(anyhow::anyhow!("Failed to get save dir"))?;
     let model_path = format!("{}/FunAudioLLM/Fun-ASR-Nano-2512/", save_dir);