Funfile 中 fun-install pip install 不支持 -r 选项

在 Funfile 中定义依赖时发现只能一个个定义，`-r` 选项不支持，无法使用 `pip install -r requirement.txt`.

RUN fun-install pip install -h

Start with the Funfile command shown in the issue: `RUN fun-install pip install -h`. Trace how `fun-install` handles pip arguments, reproduce the failure with `-r requirement.txt`, and check the existing installation flow. Done means a requirements file can be used through Funfile without breaking the current dependency syntax.

Written by the indexing model from the issue text.