Support gtk4/libadwaita for mobile support
Please note by far the quickest way to get a new feature is to file a Merge Request.
Description of the new feature
Currently gajim does not work on mobile devices like librem 5 or pinephone running pureos, mobian or postmarketOS. Updating gtk to gtk4 and libadwaita will make it adapt to small screens. Dino already has a patchset available, but there are many omemo issues with Dino.