Add support for collapsable filter (Django >= 4.1) [Alternate Version]

[mgrdcm]

The markup for change list filters changed between 4.0 and 4.1.

This is a change to add support for that, along with minor updates to styling to match newer versions of Django.

It's like #119 but is the other way to do it mentioned in #119 (comment).

[silentsokolov]

I like this version because it follows the style where only old templates are marked with a version, and the current ones have a regular name.

Thank you!

[mgrdcm]

You're welcome @silentsokolov and thanks for this library!