REST API: Switch to stable version of JSON Schema.

Props danielbachhuber.
Fixes #38635.

Built from https://develop.svn.wordpress.org/trunk@39106


git-svn-id: http://core.svn.wordpress.org/trunk@39048 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/rest-api/endpoints/class-wp-rest-comments-controller.php

@@ -1088,7 +1088,7 @@ class WP_REST_Comments_Controller extends WP_REST_Controller {
 	 */
 	public function get_item_schema() {
 		$schema = array(
-			'$schema'              => 'http://json-schema.org/draft-04/schema#',
+			'$schema'              => 'http://json-schema.org/schema#',
 			'title'                => 'comment',
 			'type'                 => 'object',
 			'properties'           => array(