Docs: Correct the type and description of `$post` parameter passed to the `attachment_fields_to_save` filter.

Props swissspidy.
Fixes #34404.
Built from https://develop.svn.wordpress.org/trunk@35374


git-svn-id: http://core.svn.wordpress.org/trunk@35338 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/media.php

@@ -662,8 +662,8 @@ function media_upload_form_handler() {
 		 *
 		 * @see wp_get_attachment_metadata()
 		 *
-		 * @param WP_Post $post       The WP_Post object.
-		 * @param array   $attachment An array of attachment metadata.
+		 * @param array $post       An array of post data.
+		 * @param array $attachment An array of attachment metadata.
 		 */
 		$post = apply_filters( 'attachment_fields_to_save', $post, $attachment );