Remove mail dependency and adapt test and CI to run mail dependant tests anyway

tests/test_mail_template.py

 ##############################################################################
 #
 #    Converter Odoo module
-#    Copyright © 2023 XCG Consulting <https://xcg-consulting.fr>
+#    Copyright © 2023, 2024 XCG Consulting <https://xcg-consulting.fr>
 #
 #    This program is free software: you can redistribute it and/or modify
 #    it under the terms of the GNU Affero General Public License as
@@ -20,6 +20,6 @@
 
 from odoo import tests  # type: ignore[import-untyped]
 
-from .. import MailTemplate
+from ..mail_template import MailTemplate
 
 
@@ -24,5 +24,6 @@
 
 
+@tests.tagged("-standard", "odoo_addons_mail")
 class Test(tests.TransactionCase):
     """Test converter that wraps ``mail.template::_render_template``."""