[FIX] mass_mailing_event: Integration tests

When running tests and `mass_mailing_list_dynamic` was installed, they failed.

mass_mailing_event/__manifest__.py

@@ -6,9 +6,9 @@
 {
     'name': 'Mass mailing event',
     'summary': 'Link mass mailing with event for excluding recipients',
-    'version': '10.0.1.0.0',
+    'version': '10.0.1.0.1',
     'category': 'Marketing',
-    'website': 'https://www.tecnativa.com',
+    'website': 'https://github.com/OCA/social',
     'author': 'Tecnativa, '
               'Odoo Community Association (OCA)',
     'license': 'AGPL-3',

mass_mailing_event/tests/test_mass_mailing_event.py

@@ -3,10 +3,12 @@
 # Copyright 2017 David Vidal <david.vidal@tecnativa.com>
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
 
-from odoo.tests import common
+from odoo.tests.common import at_install, post_install, SavepointCase
 
 
-class TestMassMailingEvent(common.SavepointCase):
+@at_install(True)
+@post_install(True)
+class TestMassMailingEvent(SavepointCase):
 
     @classmethod
     def setUpClass(cls):