<br></br> is used as newline in code blocks in markdown export #3327

Describe the Bug

When exporting page to markdown, new lines in code blocks are made with <br></br> tag, and it is obviously not being interpreted in any markdown viewer, so every code block end up as single line object with <br></br> tags inside

Steps to Reproduce

1. Create multi-line code block on a page
2. export page as markdown

Expected Behaviour

Proper newline character is used inside code blocks.

Screenshots or Additional Context

Browser Details

No response

Exact BookStack Version

v22.02.3

PHP Version

8.0

Hosting Environment

Ubuntu-based docker containers