[FIX] calendar: test_event_creation_mail was faulty

The following commit updated the test to use freezegun. One of the event start
date was not properly set before the freezegun date. As a result a notification
mail was sent.
https://github.com/odoo/odoo/commit/080688868e6acf31d3bd624798559852272bcc1a

Strangely, the test was passing during our tests even if the date was in the past.

Runbot issue: https://runbot.odoo.com/web#id=36179&view_type=form&model=runbot.build.error&menu_id=405&cids=1

closes odoo/odoo#141959

X-original-commit: f5a131931583a5d6c415742b3a65793b10e60daf
Signed-off-by: Arnaud Joset (arj) <arj@odoo.com>

addons/calendar/tests/test_calendar.py

@@ -354,7 +354,7 @@ class TestCalendar(SavepointCaseWithUserDemo):
             'allday': False,
             'recurrency': False,
             'partner_ids': partner_ids,
-            'start': "2023-10-09 08:00:00",
+            'start': "2023-10-04 08:00:00",
             'stop': "2023-10-10 08:00:00",
         })