[Bug]: Tags in OPF are not added

What happened?

I have generated OPF files as alternative metadata sidecar and used--according to the documentation--supported OPF extension <dc:tag>sample</dc:tag> but after adding the new book together with the OPF, only the tags were not loaded/added in.

The following is the relevant part of a opf file, it's structure matches that of Calibre.

<?xml version="1.0" encoding="utf-8"?>
<package xmlns="http://www.idpf.org/2007/opf" unique-identifier="uuid_id" version="2.0">
    <metadata xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:opf="http://www.idpf.org/2007/opf">
        <dc:tag>Korean Literature</dc:tag>
        <dc:tag>Completed Series</dc:tag>
    </metadata>
</package>

I added the books without metadata.json present, and this was also generated without the set tags from the OPF.

What did you expect to happen?

The tags set within the OPF are added.

Steps to reproduce the issue

1. Add an audiobook with a sidecar opf metadata file which has tags set.
2. After scanning, all fields except the tags are filled.

Audiobookshelf version

v2.36.0

How are you running audiobookshelf?

Docker

What OS is your Audiobookshelf server hosted from?

Linux

If the issue is being seen in the UI, what browsers are you seeing the problem on?

None

Logs

Additional Notes

No response