Backport pr 212 (#227)

Backport for PR #212 

Note: Dependent on langchain-ai/langchain#27114
to fix the tests failing in CI.

libs/aws/langchain_aws/chat_models/bedrock_converse.py

@@ -606,6 +606,22 @@ def _llm_type(self) -> str:
         """Return type of chat model."""
         return "amazon_bedrock_converse_chat"
 
+    @classmethod
+    def is_lc_serializable(cls) -> bool:
+        return True
+
+    @classmethod
+    def get_lc_namespace(cls) -> List[str]:
+        return ["langchain_aws", "chat_models"]
+
+    @property
+    def lc_secrets(self) -> Dict[str, str]:
+        return {
+            "aws_access_key_id": "AWS_ACCESS_KEY_ID",
+            "aws_secret_access_key": "AWS_SECRET_ACCESS_KEY",
+            "aws_session_token": "AWS_SESSION_TOKEN",
+        }
+
 
 def _messages_to_bedrock(
     messages: List[BaseMessage],