Refactor: Simplify API data serialization for patch review

[pyob-bot]

Summary of Changes

This change refactors the StatsUpdater class by simplifying how data is prepared for the /api/review_patch endpoint. Specifically, the explicit json.dumps() call for the data payload has been removed. The fetch_api function now directly receives a Python dictionary, allowing it to handle the JSON serialization internally.

Technical Impact

• Improved Readability: The code becomes cleaner and more concise by removing the manual JSON serialization step, making the intent clearer.
• Reduced Redundancy: This change assumes that the fetch_api utility (or the underlying HTTP client it uses) is capable of automatically serializing dictionary payloads to JSON for POST requests. This avoids potential double-serialization or incorrect content-type headers if fetch_api was already designed to handle dictionary inputs.
• Consistency: Promotes a more consistent pattern for passing data to fetch_api across the codebase, aligning with best practices where the HTTP client manages serialization.
• No Functional Change: The ultimate JSON payload sent to the /api/review_patch endpoint remains identical, ensuring no change in API behavior or data format.