Wagtail-orderable

- Updated documentation for wagtail 4.0 support
- Updated workflow action versions
- Allow wagtail v4.1+ (drops ability to use on a wagtail site version earlier than v4.1)
- Allow Wagtail v5 and Django v4.2

(42)

Created to nickmoreton for the update.

- Extending `Orderable` is no more mandatory if you want to use your own order field (27)
- Add `Orderable.get_sort_order_max()` to get the max "order" when instance is being created (27)
- Fix keeping current filters when sorting was reset (27)
- Fix class names (`get_extra_class_names_for_field_col` parameters were inverted) (27)
- Fix CSS which had SCSS syntax (27)

Created to th3hamm0r and DylannCordel for the update.

- Provide Github Actions script to build and publish package in PyPI
- Add support for Wagtail 3.0 and drop support for all Wagtail versions
before 2.15 (32)
- Use `pk` instead of `id` for duplicate positions (31)

Fix items
---
- TypeError when creating the first Orderable object (21)

Fix items
---
- `sort_order` duplication for items
- Wrong syntax return