Support wagtail 4.1 & Django 4.1

[nickmoreton]

This upgrades the package to use up to Wagtail 4.1 and Django 4.1

It drops support for Wagtail < 2.15 and Django < 3.2

[easherma-truth]

How does this relate to https://github.com/wagtail/wagtail-personalisation/pull/243 ?

[nickmoreton]

I can't get the sandbox to work. The requirements.txt on the sandbox says:

Django>=2.2,<2.3
wagtail>=2.6,<2.7

The documentation such as Readme.rst and Installation.rst, would need updating too, as they currently say "Wagtail Personalisation requires Wagtail 2.0 or 2.1 and Django 1.11 or 2.0.".

They needs to be updated to match the current supported versions?

@victoriachan I have update the sandbox and it's now working OK for me too. I also adjusted the supported wagtail and django versions in the docs.

[nickmoreton]

How does this relate to #243 ?

@easherma-truth Thanks for asking. That PR had work this was built off. It has been closed and those changes are part of this work now.

[zerolab]

Closing in favour of #251