[FIX] l10n_es_aeat_sii_taxfree: Test inheritance

Inherit from TestL10nEsAeatSiiBase instead of TestL10nEsAeatSii for not
repeating tests that have been already executed.

l10n_es_aeat_sii_taxfree/tests/test_l10n_es_aeat_sii_taxfree.py

@@ -1,11 +1,11 @@
 # © 2023 FactorLibre - Alejandro Ji Cheung <[email protected]>
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
 from odoo.addons.l10n_es_aeat_sii_oca.tests.test_l10n_es_aeat_sii import (
-    TestL10nEsAeatSii,
+    TestL10nEsAeatSiiBase,
 )
 
 
-class TestL10nEsAeatSiiTaxfree(TestL10nEsAeatSii):
+class TestL10nEsAeatSiiTaxfree(TestL10nEsAeatSiiBase):
     def test_tax_free_sii(self):
         """Test that the invoice is correctly generated."""
         fiscal_position = self.env["account.fiscal.position"].create(