pantheon.granite: propagate dependencies

All of these dependencies are pkg-config Requires, so dependent
packages have to depend on all of them, or they'll get messages like
this:

meson.build:17:0: ERROR: Could not generate cargs for granite:
Package gee-0.8 was not found in the pkg-config search path.
Perhaps you should add the directory containing `gee-0.8.pc'
to the PKG_CONFIG_PATH environment variable
Package 'gee-0.8', required by 'granite', not found

Hence, they should be propagated.

pkgs/desktops/pantheon/granite/default.nix

···
     wrapGAppsHook
   ];
 
-  buildInputs = [
+  propagatedBuildInputs = [
     glib
+    gsettings-desktop-schemas # is_clock_format_12h uses "org.gnome.desktop.interface clock-format"
     gtk3
     libgee
-  ];
-
-  propagatedBuildInputs = [
-    gsettings-desktop-schemas # is_clock_format_12h uses "org.gnome.desktop.interface clock-format"
   ];
 
   postPatch = ''