st/test-theme: Don't initialize GTK

St no longer requires GTK to be initialized, so this is no longer
needed (and pulls in an unnecessary GTK dependency).

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2733>

src/st/meson.build

@@ -199,7 +199,7 @@ if get_option('tests')
   test_theme = executable('test-theme',
     sources: 'test-theme.c',
     c_args: st_cflags,
-    dependencies: [mutter_test_dep, gtk_dep, libxml_dep],
+    dependencies: [mutter_test_dep, libxml_dep],
     build_rpath: mutter_typelibdir,
     link_with: libst
   )

src/st/test-theme.c

@@ -28,8 +28,6 @@
 #include <meta-test/meta-context-test.h>
 #include <meta/meta-backend.h>
 
-#include <gtk/gtk.h>
-
 static ClutterActor *stage;
 static StThemeNode *root;
 static StThemeNode *group1;
@@ -549,8 +547,6 @@ main (int argc, char **argv)
   GFile *file;
   g_autofree char *cwd = NULL;
 
-  gtk_init (&argc, &argv);
-
   /* meta_init() cds to $HOME */
   cwd = g_get_current_dir ();