Nested lists are inserted using invalid html

[orgtre]

Problem description

Thanks for this essential add-on! When creating nested lists using toggle list and indent the resulting html is technically invalid. While this doesn't cause any problems within Anki as far as I can see, it creates problems and incorrectly displayed output when trying to parse the notes using external programs such as pandoc.

For a minimal example, open a blank note, press "Toggle unordered list", write something and press enter, press "Indent", and look at the html produced:

<ul><li>item</li><ul><li><br></li></ul></ul>

According to https://stackoverflow.com/questions/5899337/proper-way-to-make-html-nested-list this is not correct while this would be:

<ul><li>item<ul><li><br></li></ul></li></ul>

I realize this might not affect many people, but if there is some quick way to fix this, it would help me a lot.

Checklist

Please replace the space inside the brackets with an x if the following items apply:

• [x] I've restarted Anki to see if it helps
• [x] I've verified that I use the latest version of the add-on by redownloading it from AnkiWeb
• [x] I've verified that I use the latest version of Anki by checking at https://apps.ankiweb.net#download
• [x] I've tried to disable other add-ons to see if there are any interactions present
• [ ] My issue disappears when I hold shift while starting Anki.
• [x] I've checked if anyone else reported this problem before by looking through the issue reports. I also checked to see if there is a section about known issues in the add-on description, documentation, or README.