Removed aws_session_token from required_keys

autogen/oai/client.py

@@ -456,7 +456,7 @@ def _configure_azure_openai(self, config: Dict[str, Any], openai_config: Dict[st
 
     def _configure_openai_config_for_bedrock(self, config: Dict[str, Any], openai_config: Dict[str, Any]) -> None:
         """Update openai_config with AWS credentials from config."""
-        required_keys = ["aws_access_key", "aws_secret_key", "aws_session_token", "aws_region"]
+        required_keys = ["aws_access_key", "aws_secret_key", "aws_region"]
 
         for key in required_keys:
             if key in config: