umi/dumi 无法引入 package/lib 目录下的 css 文件，但是可以引入 package/src 目录下的 css 文件。

[L-excellence]

import 'template/lib/index.css';

template is a dependent package.

✖ Webpack
Compiled with some errors in 328.10ms

ERROR Failed to compile with 1 errors

This dependency was not found:

• template/lib/index.css in ./src/.umi/dumi/demos/index.ts

To install it, you can run: npm install --save template/lib/index.css