week-view: fix unref of not added widget

This works in conjunction with code implemented in GcalSubscriber where
the ownership of the event widget passes into the container, so the
container is free to delete it in case it does not fit into the range
represented by the view.

src/gcal-week-view.c

@@ -888,7 +888,8 @@ gcal_week_view_add (GtkContainer *container,
         {
           //TODO: remove once the main-dev phase its over
           g_warning ("Trying to add an event with the same uuid to the view");
-          g_object_unref (widget); /* FIXME: check if this destroy it */
+          g_free (date);
+          gtk_widget_destroy (widget);
           return;
         }
     }