updated the format for the test for save_overwrite to Parquet

Signed-off-by: Minura Punchihewa <minurapunchihewa17@gmail.com>

kedro-datasets/tests/databricks/test_external_table_dataset.py

@@ -33,6 +33,7 @@ def test_save_overwrite(
         unity_ds = ExternalTableDataset(
             database="test",
             table="test_save",
+            format="parquet",
             write_mode="overwrite",
             location=f"{external_location}/test_save_overwrite_external",
         )