PkTask: Fix invalid cast from 'GsPackagekitTask' to 'GTask'

Fix the following regression from 9dfaf0d

11:30:42:759 PK  internal error: failed, but no error code: cancelled-priority
11:30:47:878 PK  internal error: failed, but no error code: cancelled-priority
11:30:55:800 GLib-GObject invalid cast from 'GsPackagekitTask' to 'GTask'
11:30:55:800 GLib-GIO g_task_get_task_data: assertion 'G_IS_TASK (task)' failed
11:30:55:801 GLib-GIO g_task_get_source_object: assertion 'G_IS_TASK (task)' failed

lib/packagekit-glib2/pk-task.c

@@ -993,7 +993,7 @@ pk_task_ready_cb (GObject *source_object, GAsyncResult *res, gpointer user_data)
 	if (state->exit_enum == PK_EXIT_ENUM_CANCELLED_PRIORITY) {
 		state->retry_id = g_timeout_add (PK_TASK_TRANSACTION_CANCELLED_RETRY_TIMEOUT,
 						 pk_task_retry_cancelled_transaction_cb,
-						 g_steal_pointer (&task));
+						 g_steal_pointer (&gtask));
 		return;
 	}