add date to eventParticipationCancelled mail

app/Mail/EventParticipationCancelledMail.php

@@ -43,6 +43,8 @@ class EventParticipationCancelledMail extends Mailable
                 'name' => $this->data['name'],
                 'lastname' => $this->data['lastname'],
                 'eventName' => $this->data['eventName'],
+                'start' => $this->data['start'],
+                'end' => $this->data['end'],
             ]
         );
     }