liaowenxiong@liaowenxiongdeMacBook-Air ~ % brew install python@3.9
==> Downloading https://mirrors.ustc.edu.cn/homebrew-bottles/xz-5.2.5.big_sur.bottle.tar.gz
Already downloaded: /Users/liaowenxiong/Library/Caches/Homebrew/downloads/df056a39b092033a98e1f8eeb9ae304920503de32f794a2d8b38ddb269ffb072--xz-5.2.5.big_sur.bottle.tar.gz
==> Downloading https://mirrors.ustc.edu.cn/homebrew-bottles/python%403.9-3.9.6.big_sur.bottle.tar.gz
#=#=#
curl: (22) The requested URL returned error: 404
Warning: Bottle missing, falling back to the default domain...
如上可知，下载 https://mirrors.ustc.edu.cn/homebrew-bottles/python%403.9-3.9.6.big_sur.bottle.tar.gz 失败了，怎么解决？
