[Feature Request]: Render thumbnails for `.cbt` ePubs

[Sola-ris]

Checklist

• I am using an up-to-date version.
• I have read the documentation.
• I have searched existing issues.

Description

TagStudio regocgnizes .cbt files as ePubs but cant generate a thumbnail since it tries to open the archive as a zipfile.

Solution

Use the builtin tarfile module to extract the thumbnail from the archive.

Alternatives

Leave it as is