Issue 3456671: Change polyfill.io to polyfill-fastly.io to reduce the risk of supply chain attack

Closes #3456671

src/Form/QuicklinkConfigForm.php

@@ -282,7 +282,7 @@ class QuicklinkConfigForm extends ConfigFormBase {
     $form['polyfill']['load_polyfill'] = [
       '#type' => 'checkbox',
       '#title' => $this->t('Load <em>Intersection Observer</em> polyfill'),
-      '#description' => $this->t('This checkbox will enable loading of necessary polyfills from <a href="https://polyfill.io" target="_blank">polyfill.io</a>. This will enable usage of Quicklink in IE11 and older versions modern browsers.'),
+      '#description' => $this->t('This checkbox will enable loading of necessary polyfills from <a href="https://polyfill-fastly.io" target="_blank">polyfill-fastly.io</a>. This will enable usage of Quicklink in IE11 and older versions modern browsers.'),
       '#default_value' => $config->get('load_polyfill'),
     ];