Fix: indentation of list with mkdocs-material as theme

[ThibaudBrrd]

Here is a fix for list indentation when using mkdocs-material as the theme.

In issue #145, I identified a problem where lists weren't indented properly when mkdocs-material was used under specific versions of WeasyPrint. So, I made some modifications to the theme/material.scss file that ensure the indentation of lists without needing to change the WeasyPrint version.