Markdown Checklist/Todo-List not hierarchical in Preview #2837

Describe the bug
Markdown Checklist/Todo-List not hierarchical in Preview. Works after saving the page.

Steps To Reproduce
Steps to reproduce the behavior:

1. Create Page and paste:

- [ ] whatever
  - [x] sub-whatever

2. see preview without indentation
3. save and see correct indentation
   Expected behavior
   Preview same as saved Page.

Screenshots

1. Editor + Preview:
   
2. Saved Page:
   

Your Configuration (please complete the following information):

• Exact BookStack Version (Found in settings): BookStack v21.05.1
• PHP Version: PHP 7.4.20
• Hosting Method (Nginx/Apache/Docker): Apache