Upgrade to Wagtail 4.0.4

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Release notes

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Video reviewing major new features in Wagtail 4.0

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It's probably important to note that these are mostly cosmetic changes to the admin interface only, and the public-facing website will continue to look and work in exactly the same way as before.

There is no preparation that needs to be done by admins before the upgrade, except to be aware that things will look a bit different. All sites will be upgraded at the same time, and there will be no downtime.

It might be worth mentioning the live preview feature, which shows what an article will look like on various screen sizes, and updates continuously as edits are made.

The main point of the upgrade is to prevent the technology behind IoGT from becoming obsolete, so the upgrade brings many smaller improvements, bug fixes and security patches, too numerous to list succinctly.