mu-plugin Testimonial Custom Post Type

cpt-testimonial.php

<?php

/**
 * @wordpress-plugin
 * Plugin Name:       Testimonials custom post type
 * Plugin URI:        [URL HERE]
 * Description:       Testimonials custom post type
 * Version:           1.0.0
 * Author:            [AUTHOR HERE]
 * Author URI:        [AUTHOR URI HERE]
 * License:           GPL-2.0+
 * License URI:       http://www.gnu.org/licenses/gpl-2.0.txt
 * Text Domain:       [TEXT DOMAIN HERE]
 * Domain Path:       /languages
 */

// If this file is called directly, die.
if (!defined('WPINC')) {
    die;
}

add_action('init', function () {
    // Register the Testimonials custom post type
    $labels = [
        'name' => _x('Testimonials', 'Post Type General Name', '[TEXT DOMAIN HERE]'),
        'singular_name' => _x('Testimonial', 'Post Type Singular Name', '[TEXT DOMAIN HERE]'),
        'menu_name' => __('Testimonials', '[TEXT DOMAIN HERE]'),
        'parent_item_colon' => __('Parent Testimonial:', '[TEXT DOMAIN HERE]'),
        'all_items' => __('All Testimonials', '[TEXT DOMAIN HERE]'),
        'view_item' => __('View Testimonial', '[TEXT DOMAIN HERE]'),
        'add_new_item' => __('Add New Testimonial', '[TEXT DOMAIN HERE]'),
        'add_new' => __('Add New', '[TEXT DOMAIN HERE]'),
        'edit_item' => __('Edit Testimonial', '[TEXT DOMAIN HERE]'),
        'update_item' => __('Update Testimonial', '[TEXT DOMAIN HERE]'),
        'search_items' => __('Search Testimonials', '[TEXT DOMAIN HERE]'),
        'not_found' => __('Not found', '[TEXT DOMAIN HERE]'),
        'not_found_in_trash' => __('Not found in Trash', '[TEXT DOMAIN HERE]'),
    ];

    $args = [
        'label' => __('testimonial', '[TEXT DOMAIN HERE]'),
        'description' => __('Testimonial', '[TEXT DOMAIN HERE]'),
        'labels' => $labels,
        'supports' => ['title', 'thumbnail', 'editor', 'excerpt'],
        'hierarchical' => false,
        'public' => true,
        'show_in_rest' => true,
        'show_ui' => true,
        'show_in_menu' => true,
        'show_in_nav_menus' => false,
        'show_in_admin_bar' => true,
        'menu_position' => 4,
        'menu_icon' => 'dashicons-thumbs-up',
        'can_export' => true,
        'has_archive' => true,
        'exclude_from_search' => false,
        'publicly_queryable' => true,
        'capability_type' => 'page',
    ];

    register_post_type('testimonials', $args);
}, 0);