Action on Custom Post publish

Issue is resolved

Updated Code

<?php
/*
Plugin Name: Send Notification CPT
Description: Declares a plugin that will create a custom post type to send notifications.
Version: 1.0
*/

if( ! defined('ABSPATH')) {
    exit;
}

// Register Custom Post Type Send Notifiction
function create_sendnotifiction_cpt() {

    $labels = array(
        'name' => _x( 'Send Notifiction', 'Post Type General Name', 'textdomain' ),
        'singular_name' => _x( 'Send Notifiction', 'Post Type Singular Name', 'textdomain' ),
        'menu_name' => _x( 'Send Notifiction', 'Admin Menu text', 'textdomain' ),
        'name_admin_bar' => _x( 'Send Notifiction', 'Add New on Toolbar', 'textdomain' ),
        'archives' => __( 'Send Notifiction Archives', 'textdomain' ),
        'attributes' => __( 'Send Notifiction Attributes', 'textdomain' ),
        'parent_item_colon' => __( 'Parent Send Notifiction:', 'textdomain' ),
        'all_items' => __( 'All Send Notifiction', 'textdomain' ),
        'add_new_item' => __( 'Add New Send Notifiction', 'textdomain' ),
        'add_new' => __( 'Add New', 'textdomain' ),
        'new_item' => __( 'New Send Notifiction', 'textdomain' ),
        'edit_item' => __( 'Edit Send Notifiction', 'textdomain' ),
        'update_item' => __( 'Update Send Notifiction', 'textdomain' ),
        'view_item' => __( 'View Send Notifiction', 'textdomain' ),
        'view_items' => __( 'View Send Notifiction', 'textdomain' ),
        'search_items' => __( 'Search Send Notifiction', 'textdomain' ),
        'not_found' => __( 'Not found', 'textdomain' ),
        'not_found_in_trash' => __( 'Not found in Trash', 'textdomain' ),
        'featured_image' => __( 'Featured Image', 'textdomain' ),
        'set_featured_image' => __( 'Set featured image', 'textdomain' ),
        'remove_featured_image' => __( 'Remove featured image', 'textdomain' ),
        'use_featured_image' => __( 'Use as featured image', 'textdomain' ),
        'insert_into_item' => __( 'Insert into Send Notifiction', 'textdomain' ),
        'uploaded_to_this_item' => __( 'Uploaded to this Send Notifiction', 'textdomain' ),
        'items_list' => __( 'Send Notifiction list', 'textdomain' ),
        'items_list_navigation' => __( 'Send Notifiction list navigation', 'textdomain' ),
        'filter_items_list' => __( 'Filter Send Notifiction list', 'textdomain' ),
    );
    $args = array(
        'label' => __( 'Send Notifiction', 'textdomain' ),
        'description' => __( '', 'textdomain' ),
        'labels' => $labels,
        'menu_icon' => 'dashicons-format-chat',
        'supports' => array('title', 'editor', 'excerpt', 'thumbnail', 'revisions', 'author', 'comments', 'trackbacks', 'page-attributes', 'post-formats', 'custom-fields'),
        'taxonomies' => array(),
        'public' => true,
        'show_ui' => true,
        'show_in_menu' => true,
        'menu_position' => 5,
        'show_in_admin_bar' => true,
        'show_in_nav_menus' => true,
        'can_export' => true,
        'has_archive' => true,
        'hierarchical' => false,
        'exclude_from_search' => false,
        'show_in_rest' => true,
        'publicly_queryable' => true,
        'capability_type' => 'post',
    );
    register_post_type( 'sendnotifiction', $args );

}
add_action( 'init', 'create_sendnotifiction_cpt', 0 );


//Notification post

function cc_publish_wpse_263985( $postid ) {

    // check if post status is 'publish'
    if ( get_post_status( $postid ) == 'publish')   {


$url="http://192.168.100.24:8181/notification/topic";

//The data you want to send via POST
$data = array( 'title' => 'Hello World',
     'message' => 'Hello',
     'token' => '',
    'topic' => 'Active');

$options = array(
  'http' => array(
    'method'  => 'POST',
    'content' => json_encode( $data ),
    'header'=>  "Content-Type: application/json\r\n" .
                "Accept: application/json\r\n"
    )
);

$context  = stream_context_create( $options );
$result = file_get_contents( $url, false, $context );
$response = json_decode( $result );

}
}
add_action( 'save_post', 'cc_publish_wpse_263985' );a
?>