在安装 katex 渲染器后，文章图片路径解析从绝对路径变为文章相对路径。

The steps to reproduce the bug are as follows:

1. Start using mathjax.
2. Follow the steps in https://hexo.fluid-dev.com/docs/guide/#latex-format to switch to katex.
3. Then, execute hexo clean -> hexo g -> hexo s in sequence.
4. Open the article page, the formulas are rendered correctly, but the images cannot be displayed, as shown above.