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/

Open pyproject.toml and inspect the CRX dependency constraint and its adjacent comment. Remove the Django upper bound so it matches the stated Wagtail constraint, then verify that the dependency metadata permits Django 6.0 and that the existing supported-version checks remain unchanged.

Written by the indexing model from the issue text.