message: fix: react is no defined when react16
diff: @@ -69,7 +69,7 @@ export default (api: IApi) => {
  path: 'Layout.tsx',
  content: `
  import { Link, useLocation, useNavigate, Outlet, useAppData, useRouteData, matchRoutes } from 'umi';
  -import { useMemo } from 'react';
  +import React, { useMemo } from 'react';
  import {
  ProLayout,
  } from "${pkgPath || '@ant-design/pro-layout'}";
  