fix: Use last_activity_at instead of updated_at for sorting (#1281)

Co-authored-by: Akash Srivastava <akash.srivastava.1911@gmail.com>

app/javascript/dashboard/store/modules/conversations/index.js

@@ -92,6 +92,7 @@ export const mutations = {
     );
     if (previousMessageIndex === -1) {
       chat.messages.push(message);
+      chat.timestamp = message.created_at;
       if (_state.selectedChatId === message.conversation_id) {
         window.bus.$emit('scrollToMessage');
       }