fixed the lost copy_metadata attrs from test

apps/hiopy/tests/create_simple_dataset.sh.in

@@ -12,9 +12,9 @@ z = zarr.open("${dataset}")
 hc.add_healpix_hierarchy(z, order=3)
 hc.add_time(z, "2000-01-01", "2000-01-01T00:01:00", 3)
 
-hc.add_variable(z, "x", "simple_source", "simple_grid")
-hc.add_variable(z, "y", "simple_source", "simple_grid")
-hc.add_variable(z, "z", "simple_source", "simple_grid")
+hc.add_variable(z, "x", "simple_source", "simple_grid", attributes={"hiopy::copy_metadata": True})
+hc.add_variable(z, "y", "simple_source", "simple_grid", attributes={"hiopy::copy_metadata": True})
+hc.add_variable(z, "z", "simple_source", "simple_grid", attributes={"hiopy::copy_metadata": True})
 hc.add_variable(z, "clock", "simple_source", "simple_grid", attributes={"hiopy::copy_metadata": True})
 
 zarr.consolidate_metadata(z.store)