[gtk/clipboard-demo-fixes] widget-factory: Update copyright year

[Matthias Clasen <matthiasc src gnome org>]

commit 6f7bd37aebb0854de25f9f82b12b19688701e97f
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Apr 26 00:45:06 2020 -0400

    widget-factory: Update copyright year

 demos/widget-factory/widget-factory.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/demos/widget-factory/widget-factory.c b/demos/widget-factory/widget-factory.c
index f8c0b86229..4b728c3a6c 100644
--- a/demos/widget-factory/widget-factory.c
+++ b/demos/widget-factory/widget-factory.c
@@ -280,7 +280,7 @@ activate_about (GSimpleAction *action,
   gtk_show_about_dialog (GTK_WINDOW (gtk_application_get_active_window (app)),
                          "program-name", "GTK Widget Factory",
                          "version", version,
-                         "copyright", "© 1997—2019 The GTK Team",
+                         "copyright", "© 1997—2020 The GTK Team",
                          "license-type", GTK_LICENSE_LGPL_2_1,
                          "website", "http://www.gtk.org";,
                          "comments", "Program to demonstrate GTK themes and widgets",