javascript - Notification functionality using ajax php

one text

Here I am stuck in a problem that is not bigger but I don't know why it's not working. There is a table name task and a column status through a notification is shown on a webpage. I am using ajax to update column values but the problem is ajax request is executed but the PHP file code is not running, I don't know why is this happening.

PHP code to show data

<button class="notification-btn">
    
    <ul class="notification-drop">
      <li class="item">
      <svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none"
      stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"
      class="feather feather-bell">
      <path d="M18 8A6 6 0 0 0 6 8c0 7-3 9-3 9h18s-3-2-3-9" />
      <path d="M13.73 21a2 2 0 0 1-3.46 0" />
    </svg>
        <span class="btn__badge pulse-button" id="noti_hide">
          <?php
            $qs11 = "SELECT task FROM `task` where employee_id='{$session_id}' AND status='unseen'";
            // echo "$q11";
            // die();
            $trs1 = mysqli_query($con, $qs11) or die("query failed for row");
            $trows1 = mysqli_num_rows($trs1);
            
            echo $trows1;
          ?>
        </span>
        <ul>
        <?php
          $qz1 = "SELECT task FROM `task` where employee_id='{$session_id}' AND status='unseen'";
          $result = mysqli_query($con, $qz1) or die("query 1 failed ");
          if (mysqli_num_rows($result) > 0 ) {
            while ($row = mysqli_fetch_assoc($result)) {
              echo '<li>'.$row['task'].'</li>';
            }
          }
        ?>
        </ul>
      </li>
    </ul>
  </button>

ajax code

document).ready(function() {
$(".notification-btn .item").on('click',function() {
  $(this).find('ul').toggle();
  $.ajax({
    url : "update.php",
    type : "POST",
    data : 'get',
    success : function(data){
      $('#noti_hide').fadeOut('slow');
      console.log("success");
    },
    error: function(){
      console.log("error");
    }
  });
});
});

update.php

<?php
include('db.php');
session_start();
if ($_SESSION['employee_name'] == "") {
    header("location:index.php");
}

$session_id = $_SESSION['employee_id'];

$upd_qry = "UPDATE `task` SET status='seen' WHERE employee_id=$session_id AND status='unseen'";
mysqli_query($con,$upd_qry);
?>