Regenerate chat client (#6977)

Generated in GitHub action: https://togithub.com/googleapis/googleapis/google-api-php-client-services/actions/workflows/codegen.yaml

Author: yoshi-code-bot

src/HangoutsChat.php

@@ -56,6 +56,9 @@ class HangoutsChat extends \Google\Service
   /** On their own behalf, apps in Google Chat can see, add, update, and remove members from conversations and spaces. */
   const CHAT_APP_MEMBERSHIPS =
       "https://www.googleapis.com/auth/chat.app.memberships";
+  /** On their own behalf, apps in Google Chat can see all messages and their associated reactions and message content. */
+  const CHAT_APP_MESSAGES_READONLY =
+      "https://www.googleapis.com/auth/chat.app.messages.readonly";
   /** On their own behalf, apps in Google Chat can create conversations and spaces and see or update their metadata (including history settings and access settings). */
   const CHAT_APP_SPACES =
       "https://www.googleapis.com/auth/chat.app.spaces";