Fix: Update Twig_Markup Usage for Compatibility with Pico 3.0

[PxaMMaxP]

Introduction

This Pull Request addresses the compatibility issue with the Pico:pico-3.0 branch, as discussed in Issue #16.

Change Details

• Updated the usage of Twig_Markup to \Twig\Markup to align with the changes in PicoCMS 3.0.
• The modification ensures that the plugin remains compatible with PicoCMS 3.0 while maintaining backward compatibility with older versions.

Code Modification

- $twigVariables['toc'] = new Twig_Markup($this->toc_element_xml, 'UTF-8');
+ $twigVariables['toc'] = new \Twig\Markup($this->toc_element_xml, 'UTF-8');

Impact

• This change is critical for the plugin to function correctly with the latest version of PicoCMS (Pico 3.0).
• Ensures that the plugin remains usable for users who upgrade to PicoCMS 3.0, as well as those on older versions.