Replace django-redis by Django's core?

[browniebroke]

Description

Django 4.0 introduced a Redis backend for caching, but this template still uses the django-redis package. There might be a good reason for it, but at this point I'm not sure and would like to ask the question.

There is a thread in the django-redis repo with some questions & answers which may help us make a decision: jazzband/django-redis#585. The repo has still a lot of activity so it's far from being unmaintained and has still some advantages vs the backend from Django core.

If we switch, we need to ensure that it works as expected with secure connection strings rediss://... which we just added support (#5500).

Rationale

One fewer dependency to install