fix: update model name from Qwen3-30B-A3B to Qwen3.5-35B-A3B-FP8

The previous model name doesn't exist on the Doubleword platform.

Author: sejori

src/oss/python/integrations/chat/doubleword.mdx

@@ -71,7 +71,7 @@ Now we can instantiate our model object and generate chat completions:
 from langchain_doubleword import ChatDoubleword
 
 model = ChatDoubleword(
-    model="Qwen/Qwen3-30B-A3B",
+    model="Qwen/Qwen3.5-35B-A3B-FP8",
     temperature=0,
     max_tokens=1024,
     max_retries=2,
@@ -151,7 +151,7 @@ import asyncio
 from langchain_doubleword import ChatDoublewordBatch
 
 batch_model = ChatDoublewordBatch(
-    model="Qwen/Qwen3-30B-A3B",
+    model="Qwen/Qwen3.5-35B-A3B-FP8",
     temperature=0,
 )