Added model_name property into ChatAnthropic

As model_name is used to retrieve the name of the model in other providers, it will be helpful to implement similar property into Anthropic package as well.

libs/partners/anthropic/langchain_anthropic/chat_models.py

@@ -600,6 +600,11 @@ class Joke(BaseModel):
     message chunks will be generated during the stream including usage metadata.
     """
 
+    @property
+    def model_name(self) -> str:
+        """Alias for model"""
+        return self.model
+
     @property
     def _llm_type(self) -> str:
         """Return type of chat model."""