dlib 安装失败：legacy-install-failure 错误解决方法

安装 dlib 时遇到错误 'legacy-install-failure'，这通常不是 pip 的问题，而是 dlib 本身的问题。

'note: This error originates from a subprocess, and is likely not a problem with pip.' 'error: legacy-install-failure'

'× Encountered error while trying to install package.' '╰─> dlib'

'note: This is an issue with the package mentioned above, not pip.' 'hint: See above for output from the failure.' 'WARNING: Ignoring invalid distribution -ip (c:\users\fanzhu\appdata\local\programs\python\python38\lib\site-packages)' 'WARNING: Ignoring invalid distribution -ip (c:\users\fanzhu\appdata\local\programs\python\python38\lib\site-packages)' 'WARNING: Ignoring invalid distribution -ip (c:\users\fanzhu\appdata\local\programs\python\python38\lib\site-packages)'

建议检查 dlib 的安装步骤是否正确，并查看上面的输出信息以获取更多信息。同时，也可以尝试更新 pip 和 setuptools，并在安装 dlib 之前安装依赖项。