Update the Wagtail version from 6 to 7.2

[Alex-Pavlyuk]

We need to actualise the site core version, apply all security updates, etc

[Alex-Pavlyuk]

it was done, now it is in testing. At the same time we build the regression testing list for the site

Update (13/01/26): everything works well as I see. The resgression tests list is in progress