Fix data_sync startup crash by properly invoking async main (#11879)

### What problem does this PR solve?

This PR fixes a startup crash in the data_sync_0 service caused by an
incorrect asyncio.run call. The main coroutine was being passed as a
function reference instead of being invoked, which raised:

`ValueError: a coroutine was expected, got <function main ...>
`

What I changed

- Updated the entrypoint in sync_data_source.py to correctly invoke the
coroutine with `asyncio.run(main())`.

Testing
- No tested.

Related Issue
Fixes https://github.com/infiniflow/ragflow/issues/11878

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

rag/svr/sync_data_source.py

@@ -714,4 +714,4 @@ async def main():
 if __name__ == "__main__":
     faulthandler.enable()
     init_root_logger(CONSUMER_NAME)
-    asyncio.run(main)
+    asyncio.run(main())