[FIX] mail: missing translation

closes odoo/odoo#29356

addons/mail/i18n/mail.pot

@@ -5440,6 +5440,12 @@ msgstr ""
 msgid "You cannot delete those groups, as the Whole Company group is required by other modules."
 msgstr ""
 
+#. module: mail
+#: code:addons/mail/models/mail_thread.py:2358
+#, python-format
+msgid "You have been assigned to %s"
+msgstr ""
+
 #. module: mail
 #: model_terms:ir.ui.view,arch_db:mail.message_user_assigned
 msgid "You have been assigned to the"

addons/mail/models/mail_thread.py

@@ -2355,7 +2355,7 @@ class MailThread(models.AbstractModel):
             assignation_msg = view.render(values, engine='ir.qweb', minimal_qcontext=True)
             assignation_msg = self.env['mail.thread']._replace_local_links(assignation_msg)
             record.message_notify(
-                subject='You have been assigned to %s' % record.display_name,
+                subject=_('You have been assigned to %s') % record.display_name,
                 body=assignation_msg,
                 partner_ids=[(4, pid) for pid in partner_ids],
                 record_name=record.display_name,