[seahorse] pgp: KeyServerResults: fix type warning.

[Niels De Graef <nielsdg src gnome org>]

commit 9ec22a348708c279bd4216121c69965e84a17f40
Author: Niels De Graef <nielsdegraef gmail com>
Date:   Tue Aug 14 00:34:49 2018 +0200

    pgp: KeyServerResults: fix type warning.

 pgp/seahorse-keyserver-results.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/pgp/seahorse-keyserver-results.c b/pgp/seahorse-keyserver-results.c
index eee6a2c1..5ecf201d 100644
--- a/pgp/seahorse-keyserver-results.c
+++ b/pgp/seahorse-keyserver-results.c
@@ -109,7 +109,7 @@ on_key_list_button_pressed (GtkTreeView* view, GdkEventButton* event, SeahorseKe
        if (event->button == 3)
                seahorse_catalog_show_context_menu (SEAHORSE_CATALOG (self),
                                                   SEAHORSE_CATALOG_MENU_OBJECT,
-                                                  event);
+                                                  (GdkEvent *) event);
        return FALSE;
 }