removed importing unused component

src/client/js/components/Admin/SlackIntegration/CustomBotWithProxySettings.jsx

@@ -8,7 +8,6 @@ import { toastSuccess, toastError } from '../../../util/apiNotification';
 import CustomBotWithProxyIntegrationCard from './CustomBotWithProxyIntegrationCard';
 import WithProxyAccordions from './WithProxyAccordions';
 import DeleteSlackBotSettingsModal from './DeleteSlackBotSettingsModal';
-import AdminUpdateButtonRow from '../Common/AdminUpdateButtonRow';
 
 const logger = loggerFactory('growi:SlackBotSettings');