fix(agents-api): Change wrapped assertion error status code to 400 (#838

)

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> [!IMPORTANT]
> Add handling for `AssertionError` in `prepare_execution_input.py`,
mapping it to HTTP 429 error.
> 
>   - **Error Handling**:
> - Add handling for `AssertionError` in `prepare_execution_input.py`,
mapping it to `HTTPException` with status code 429.
> 
> <sup>This description was created by </sup>[<img alt="Ellipsis"
src="https://img.shields.io/badge/Ellipsis-blue?color=175173">](https://www.ellipsis.dev?ref=julep-ai%2Fjulep&utm_source=github&utm_medium=referral)<sup>
for 901bec8. It will automatically
update as commits are pushed.</sup>


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agents-api/agents_api/models/execution/prepare_execution_input.py

@@ -31,7 +31,7 @@
         QueryException: partialclass(HTTPException, status_code=400),
         ValidationError: partialclass(HTTPException, status_code=400),
         TypeError: partialclass(HTTPException, status_code=400),
-        AssertionError: lambda e: HTTPException(status_code=422, detail=str(e)),
+        AssertionError: lambda e: HTTPException(status_code=400, detail=str(e)),
     }
 )
 @wrap_in_class(