Fix: Gitter: unread message count not working

fixes https://github.com/ramboxapp/community-edition/issues/2413
fixes https://github.com/ramboxapp/community-edition/issues/2391
fixes https://github.com/ramboxapp/community-edition/issues/2757

api/services.json

@@ -353,7 +353,7 @@
         "type": "messaging",
         "allow_popups": false,
         "manual_notifications": false,
-        "js_unread": "function checkUnread(){var e=document.getElementsByClassName(\"room-item__unread-indicator\"),t=0;for(i=0;i<e.length;i++)t+=isNaN(parseInt(e[i].innerHTML.trim())) ? 0 : parseInt(e[i].innerHTML.trim());updateBadge(t)}function updateBadge(e){e>=1?document.title=\"(\"+e+\") \"+originalTitle:document.title=originalTitle}var originalTitle=document.title;setInterval(checkUnread,3000);",
+        "js_unread": "function checkUnread(){let e=0;document.querySelectorAll(\".unread-indicator\").forEach(n=>parseInt(n.innerText)&&(e+=parseInt(n.innerText))),updateBadge(e)}function updateBadge(e){e&&e>=1?rambox.setUnreadCount(e):rambox.clearUnreadCount()}setInterval(checkUnread,3e3);",
         "userAgent": "",
         "note": "",
         "titleBlink": false,