fix: explicitly lookup AWS_ENDPOINT_URL_LAMBDA while using preview lambda model (#22)

Author: bchampp

src/aws_durable_execution_sdk_python/lambda_service.py

@@ -862,11 +862,19 @@ def initialize_local_runner_client() -> LambdaClient:
     @staticmethod
     def initialize_from_env() -> LambdaClient:
         LambdaClient.load_preview_botocore_models()
-        client = boto3.client(
-            "lambdainternal",
-        )
 
-        logger.debug("Initialized lambda client")
+        """
+        TODO - we can remove this when were using the actual lambda client,
+        but we need this with the preview model because boto won't match against lambdainternal.
+        """
+        endpoint_url = os.getenv("AWS_ENDPOINT_URL_LAMBDA", None)
+        if not endpoint_url:
+            client = boto3.client(
+                "lambdainternal",
+            )
+        else:
+            client = boto3.client("lambdainternal", endpoint_url=endpoint_url)
+
         return LambdaClient(client=client)
 
     def checkpoint(