External Libraries: Update the whatwg-fetch polyfill library.

This updates the `whatwg-fetch` library from version `3.6.17` to `3.6.20`, the latest current version.

This library is included and registered within WordPress as the `wp-polyfill-fetch` script but is no longer used by WordPress itself. Updates are provided as a courtesy, and all projects using this polyfill should reevaluate usage.

Props manooweb.
Fixes #60514.

git-svn-id: https://develop.svn.wordpress.org/trunk@58860 602fd350-edb4-49c9-b593-d223f7449a82

package.json

@@ -167,7 +167,7 @@
 		"react-is": "18.3.1",
 		"regenerator-runtime": "0.14.1",
 		"underscore": "1.13.6",
-		"whatwg-fetch": "3.6.17",
+		"whatwg-fetch": "3.6.20",
 		"wicg-inert": "3.1.2"
 	},
 	"scripts": {

src/wp-includes/script-loader.php

@@ -114,7 +114,7 @@ function wp_default_packages_vendor( $scripts ) {
 		'regenerator-runtime'         => '0.14.1',
 		'moment'                      => '2.29.4',
 		'lodash'                      => '4.17.21',
-		'wp-polyfill-fetch'           => '3.6.17',
+		'wp-polyfill-fetch'           => '3.6.20',
 		'wp-polyfill-formdata'        => '4.0.10',
 		'wp-polyfill-node-contains'   => '4.8.0',
 		'wp-polyfill-url'             => '3.6.4',