fix type assertions in test

Author: rabernat

tests/v3/test_codecs/test_vlen.py

@@ -70,12 +70,12 @@ async def test_vlen_bytes(store: Store) -> None:
 
     a[:, :] = data
     assert np.array_equal(data, a[:, :])
-    # assert a.metadata.data_type == DataType.string
-    # assert a.dtype == expected_zarr_string_dtype
+    assert a.metadata.data_type == DataType.bytes
+    assert a.dtype == "O"
 
     # test round trip
     b = Array.open(sp)
     assert isinstance(b.metadata, ArrayV3Metadata)  # needed for mypy
     assert np.array_equal(data, b[:, :])
-    # assert b.metadata.data_type == DataType.string
-    # assert a.dtype == expected_zarr_string_dtype
+    assert b.metadata.data_type == DataType.bytes
+    assert a.dtype == "O"