Update tax_rate_factory
Update tax_rate_factory

The amount is a decimal, so `0.1` here is actually a 10% tax rate. `100` is ridiculous (10000% tax).

Also, the factory fails without a calculator, and it should explicitly be a DefaultTax calculator or it will not be correct.

lin-d-hop/openfoodnetwork,Matt-Yorkley/openfoodnetwork,lin-d-hop/openfoodnetwork,openfoodfoundation/openfoodnetwork,lin-d-hop/openfoodnetwork,mkllnk/openfoodnetwork,openfoodfoundation/openfoodnetwork,openfoodfoundation/openfoodnetwork,mkllnk/openfoodnetwork,Matt-Yorkley/openfoodnetwork,lin-d-hop/openfoodnetwork,mkllnk/openfoodnetwork,mkllnk/openfoodnetwork,openfoodfoundation/openfoodnetwork,Matt-Yorkley/openfoodnetwork,Matt-Yorkley/openfoodnetwork