[4.1] Schedule Tasks notification dates

Change to use DATE_FORMAT_LC instead of RFC822 to enable translated dates in the notification emails.

To test make sure that your test site will send emails
Create a scheduled task and set the notification for task success to enabled
Install russian language and set to default for admin
Go to the list of scheduled tasks and perform a test run of the scheduled task.

### Before PR
The email will look similar to
> Задача #3, checking images, успешно выполнена Fri, 15 Apr 2022 08:54:34 +0000.

### After PR
The email will look similar to
> Задача #3, checking images, успешно выполнена Пятница, 15 апреля 2022, 09:09.

plugins/system/tasknotification/tasknotification.php

@@ -242,7 +242,7 @@ public function notifyFatalRecovery(Event $event): void
 	 */
 	private function getDataFromTask(Task $task): array
 	{
-		$lockOrExecTime = Factory::getDate($task->get('locked') ?? $task->get('last_execution'))->toRFC822();
+		$lockOrExecTime = Factory::getDate($task->get('locked') ?? $task->get('last_execution'))->format(Text::_('DATE_FORMAT_LC2'));
 
 		return [
 			'TASK_ID'        => $task->get('id'),