Drop support for Django 3.2

[sliverc]

Description of the Change

Run django-upgrade --target-version 4.2

Checklist

• [x] PR only contains one change (considered splitting up PR)
• [x] unit-test added
• [ ] documentation updated
• [x] CHANGELOG.md updated (only for user relevant changes)
• [x] author name in AUTHORS

[n2ygk]

codecov having performance problems: https://status.codecov.com/incidents/wxf45dcr5ysr so merging this