Update GTK to version 4.20.1

[Beryesa]

Hi, a new stable gtk release in town :P
Probably other libs will also need updates, but I haven't messed with the appstream patch for libadwaita 1.8 etc

There's also the shadow issues again but I'm not sure if it's an upstream regression or renderer misconfiguration;
haven't got 4.20.1 over the msys2 packages to check against that yet

Marking as Draft

[danyeaw]

Hey @Beryesa - thanks so much for the contribution! You'll need to update libadwaita as well with the same PR I think.

[Beryesa]

Thanks, will get on it
Btw what do you think about the possibility to patch appstream to build instead of stripping it out of libadwaita?
Based on this ximion/appstream#541

[danyeaw]

Hi @Beryesa, I would be ok with patching Appstream instead of libadwaita if someone can get it to build. I have no idea what is required to get clang set up.

[danyeaw]

Hi @Beryesa, I repatched libadwaita and pushed it to your branch. Are you good for us to merge this?

[Beryesa]

Oh, sure of course, thanks, take it as you wish – I didn't have the chance over the weekend. 😅