[IMP] l10n_es_edi_sii: put the gipuzkoa certificate by default

This way, the demo company is easier to play with as
a certificate is already there.

Part-of: odoo/odoo#109907

addons/l10n_es_edi_sii/__manifest__.py

@@ -40,6 +40,7 @@
         'views/l10n_es_edi_certificate_views.xml',
         'views/res_config_settings_views.xml',
     ],
+    'demo': ['demo/demo_certificate.xml'],
     'external_dependencies': {
         'python': ['pyOpenSSL'],
     },

addons/l10n_es_edi_sii/demo/demo_certificate.xml

+<?xml version="1.0" encoding="utf-8"?>
+<odoo>
+    <record id="demo_certificate" model="l10n_es_edi.certificate">
+        <field name="content" type="base64" file="l10n_es_edi_sii/demo/certificates/sello_entidad_act.p12"/>
+        <field name="password">IZDesa2021</field>
+        <field name="company_id" ref="l10n_es.demo_company_es"/>
+    </record>
+</odoo>