refactor: use payload.to_string() instead of serde_json::to_string

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: psteinroe

src/sink/sqs.rs

@@ -198,17 +198,9 @@ impl Sink for SqsSink {
                 let mut entries = Vec::with_capacity(chunk.len());
 
                 for (idx, event) in chunk {
-                    let message_body = serde_json::to_string(&event.payload).map_err(|e| {
-                        etl::etl_error!(
-                            etl::error::ErrorKind::InvalidData,
-                            "Failed to serialize payload to JSON",
-                            e.to_string()
-                        )
-                    })?;
-
                     let entry = SendMessageBatchRequestEntry::builder()
                         .id(idx.to_string())
-                        .message_body(message_body)
+                        .message_body(event.payload.to_string())
                         .build()
                         .map_err(|e| {
                             etl::etl_error!(