* [FIX] account_product_fiscal_classification : In a context of product creation, if classification is not provided (in import context for exemple), _find_or_create_classification should be allways called to ensure all templates have a classification

* [FIX] account_product_fiscal_classification : if a code make a write vals={supplier_taxes_id: []} this should raise the call of _find_or_create_classification

* [FIX] account_product_fiscal_classification/tests : assertNotEquals is deprecated

* [FIX] account_product_fiscal_classification : explicit supplier and customer taxes in test, to avoid bug if default taxes are defined