[3.10] [PHP 8.1] Fixes Table User for Date/Date.php warning on login (j…

…oomla#36799)

Fixes `Deprecated: DateTime::__construct(): Passing null to parameter #1 ($datetime) of type string is deprecated in /home/beat/www/j/libraries/src/Date/Date.php on line 112` error on login

libraries/src/Table/User.php

@@ -478,7 +478,7 @@ public function setLastVisit($timeStamp = null, $userId = null)
 		}
 
 		// If no timestamp value is passed to function, than current time is used.
-		$date = \JFactory::getDate($timeStamp);
+		$date = \JFactory::getDate($timeStamp === null ? 'now' : $timeStamp);
 
 		// Update the database row for the user.
 		$db = $this->_db;