Fix relative path traversal in twill:staticdocs:serve

[ouuan]

Description

This fixes the relative path traversal vulnerability in the twill:staticdocs:serve command, which allows remote attackers to access any file on the host filesystem.

However, in reality, no one uses this command to host the docs while exposing it to the Internet.

Related Issues

Rejected as a security vulnerability in https://github.com/area17/twill/security/advisories/GHSA-9wwx-w6vv-q72c

this is not a vulnerability in the area17/twill software published on Packagist, as the command you are referring to is made for project maintainers in a local environnement, to contribute to the docs.

[CLAassistant]

All committers have signed the CLA.