Fix failing unit tests

Author: t-hamano

tests/phpunit/tests/post.php

@@ -826,7 +826,7 @@ public function test_use_block_editor_for_post() {
 	 */
 	public function test_wp_insert_post_handle_malformed_post_date( $input, $expected ) {
 		$post = array(
-			'post_author'  => self::$editor_id,
+			'post_author'  => self::$user_ids['editor'],
 			'post_status'  => 'publish',
 			'post_content' => 'content',
 			'post_title'   => 'title',