Unescape HTML entities in rich web push notifications in web UI (#7569)

app/javascript/mastodon/service_worker/web_push_notifications.js

 import IntlMessageFormat from 'intl-messageformat';
 import locales from './web_push_locales';
+import { unescape } from 'lodash';
 
 const MAX_NOTIFICATIONS = 5;
 const GROUP_TAG = 'tag';
@@ -60,7 +61,7 @@ const formatMessage = (messageId, locale, values = {}) =>
   (new IntlMessageFormat(locales[locale][messageId], locale)).format(values);
 
 const htmlToPlainText = html =>
-  html.replace(/<br\s*\/?>/g, '\n').replace(/<\/p><p>/g, '\n\n').replace(/<[^>]*>/g, '');
+  unescape(html.replace(/<br\s*\/?>/g, '\n').replace(/<\/p><p>/g, '\n\n').replace(/<[^>]*>/g, ''));
 
 const handlePush = (event) => {
   const { access_token, notification_id, preferred_locale, title, body, icon } = event.data.json();