Please remove the upper bound on Django

#### Describe the bug
Wagtail works like a charm with Django 6.0+ but I can’t install CRX because of that upper bound.
The comment in pyproject.toml is even misguiding:

```toml
dependencies = [
...
"Django>=4.2,<6.0", # should be the same as wagtail
]
```

The Wagtail’s pyproject.toml:

```toml
dependencies = [
...
"Django>=4.2"
]
```

I see that CRX is tested against 5.2 and below, so it’s my responsibility to dare use it with Django 6.

---

Some opinion on the subject: https://iscinumpy.dev/post/bound-version-constraints/