wip build: Build depend on newer GTK
We need 3.24.8 at runtime to render system modal dialogs correctly. Express this as a build time requirement to make people aware.
This breaks building on plain Debian Buster.
i'm marking this as wip since i'm not sure it's worth tripping up people right now.
Signed-off-by: Guido Günther guido.gunther@puri.sm
Edited by Guido Gunther