fix: encode localmode payload to UTF-8 (#2430)

Co-authored-by: Steven Anton <[email protected]>
Co-authored-by: icywang86rui <[email protected]>

Author: 3 people

src/sagemaker/local/local_session.py

@@ -469,6 +469,9 @@ def invoke_endpoint(
         if InferenceId is not None:
             headers["X-Amzn-SageMaker-Inference-Id"] = InferenceId
 
+        # The http client encodes all strings using latin-1, which is not what we want.
+        if isinstance(Body, str):
+            Body = Body.encode("utf-8")
         r = self.http.request("POST", url, body=Body, preload_content=False, headers=headers)
 
         return {"Body": r, "ContentType": Accept}