model(vlm): mistral 3.1 (#5099)

Co-authored-by: KivenChen <sleigh-queue-0y@icloud.com>

test/srt/test_vision_openai_server.py

@@ -664,6 +664,28 @@ class TestPixtralServer(TestOpenAIVisionServer):
         pass
 
 
+class TestMistral3_1Server(TestOpenAIVisionServer):
+    @classmethod
+    def setUpClass(cls):
+        cls.model = "unsloth/Mistral-Small-3.1-24B-Instruct-2503"
+        cls.base_url = DEFAULT_URL_FOR_TEST
+        cls.api_key = "sk-123456"
+        cls.process = popen_launch_server(
+            cls.model,
+            cls.base_url,
+            timeout=DEFAULT_TIMEOUT_FOR_SERVER_LAUNCH,
+            other_args=[
+                "--trust-remote-code",
+                "--mem-fraction-static",
+                "0.8",
+            ],
+        )
+        cls.base_url += "/v1"
+
+    def test_video_chat_completion(self):
+        pass
+
+
 class TestDeepseekVL2Server(TestOpenAIVisionServer):
     @classmethod
     def setUpClass(cls):