Plugins: Correct the item schema for the plugins REST API endpoint.

The `author` property contains the string name of the plugin author.

Props narenin.

Fixes #61920


git-svn-id: https://develop.svn.wordpress.org/trunk@59031 602fd350-edb4-49c9-b593-d223f7449a82

Author: johnbillion

src/wp-includes/rest-api/endpoints/class-wp-rest-plugins-controller.php

@@ -913,7 +913,7 @@ public function get_item_schema() {
 				),
 				'author'       => array(
 					'description' => __( 'The plugin author.' ),
-					'type'        => 'object',
+					'type'        => 'string',
 					'readonly'    => true,
 					'context'     => array( 'view', 'edit' ),
 				),