Upgrade to Django 5.1

[jeremystretch]

Proposed Changes

Migrate from Django 5.0 to Django 5.1.

Justification

Django 5.1 was released in August 2024.

[arthanson]

Ran into this issue: https://forum.djangoproject.com/t/non-editable-error-for-a-genericforeignkey-in-an-modelform-when-updating-to-version-5-1/35033