[Data] Fix bug where _StatsActor errors with PandasBlock (#40481)

StatsActor errors if your dataset contains pandas blocks.

Signed-off-by: Balaji Veeramani <balaji@anyscale.com>

python/ray/data/_internal/pandas_block.py

@@ -238,7 +238,7 @@ def num_rows(self) -> int:
         return self._table.shape[0]
 
     def size_bytes(self) -> int:
-        return self._table.memory_usage(index=True, deep=True).sum()
+        return int(self._table.memory_usage(index=True, deep=True).sum())
 
     def _zip(self, acc: BlockAccessor) -> "pandas.DataFrame":
         r = self.to_pandas().copy(deep=False)