Add admin notifications for new Mastodon versions (#26582)

lib/tasks/mastodon.rake

@@ -424,6 +424,10 @@ namespace :mastodon do
         end
       end
 
+      prompt.say "\n"
+
+      env['UPDATE_CHECK_URL'] = '' unless prompt.yes?('Do you want Mastodon to periodically check for important updates and notify you? (Recommended)', default: true)
+
       prompt.say "\n"
       prompt.say 'This configuration will be written to .env.production'