fix: improve __dir__ method to return sorted unique attributes

Author: kosiew

python/datafusion/table_provider.py

@@ -88,7 +88,7 @@ def __getattr__(self, name: str) -> Any:
 
     def __dir__(self) -> list[str]:
         """Expose delegated attributes via :func:`dir`."""
-        return dir(self._table_provider) + super().__dir__()
+        return sorted(set(super().__dir__()) | set(dir(self._table_provider)))
 
     def __repr__(self) -> str:  # pragma: no cover - simple delegation
         """Return a representation of the wrapped provider."""