update deprecated API call

src/plugins/converse-rai.js

@@ -25,7 +25,7 @@
             Backbone = converse.env.Backbone;
             dayjs = converse.env.dayjs;
 
-            _converse.api.settings.update({
+            _converse.api.settings.extend({
                 rai_notification: true,
                 rai_notification_label: "Room Activity Indicator"
             });