Fix running focus-chain tests in ci

The widget-factory ui files require geettings
(for the color chooser), so set GSETTINGS_SCHEMA_DIR.

testsuite/gtk/meson.build

@@ -185,6 +185,7 @@ foreach test : focus_chain_tests
               'GDK_DEBUG=default-settings',
               'GTK_CSD=1',
               'G_ENABLE_DIAGNOSTIC=0',
+              'GSETTINGS_SCHEMA_DIR=@0@'.format(gtk_schema_build_dir),
               'G_TEST_SRCDIR=@0@'.format(meson.current_source_dir()),
               'G_TEST_BUILDDIR=@0@'.format(meson.current_build_dir())
              ],