[pygobject] Use quark variable for class on gtype

[Christoph Reiter <creiter src gnome org>]

commit 26c334b505ac7f251e7e8c36deca0e119eb030b5
Author: Arjan Molenaar <gaphor gmail com>
Date:   Sun Aug 22 19:39:39 2021 +0200

    Use quark variable for class on gtype

 gi/gimodule.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/gi/gimodule.c b/gi/gimodule.c
index 2d1dfe20..4668369c 100644
--- a/gi/gimodule.c
+++ b/gi/gimodule.c
@@ -1312,7 +1312,7 @@ pyg_type_register(PyTypeObject *class, const char *type_name)
 
     /* store pointer to the class with the GType */
     Py_INCREF(class);
-    g_type_set_qdata(instance_type, g_quark_from_string("PyGObject::class"),
+    g_type_set_qdata(instance_type, pygobject_class_key,
                     class);
 
     /* Mark this GType as a custom python type */