Submission link errors

[mihranmiroyan]

The link to the submission zip file generated by export cell throws "File is not UTF-8 encoded" error.

To Reproduce
Steps to reproduce the behavior:

1. otter assign lab01.ipynb.zip
2. run the cells of lab01.ipynb from the autograder folder
3. click on the link generated by the export cell.
4. throws an error:

Expected behavior
When clicking on the submission link, it should download the submission zip file.

Versions
Python 3.11.0; Otter-grader 5.1.1

Additional context
Datahub environment; we just downgraded otter to 4.4.1 (it was 5.1.1).

Requirement.txt for otter: requirements.txt

[balajialg]

Additional info about this behavior across other versions:

Otter versions 5.0.0 and 5.0.2 - Reported error messages and didn't generate the link to download the zip file
Otter versions 5.1.1 and 5.1.2 - Clicking the zip file generated the UTF 8 error reported above!