Connect gpg agent action correctly

Fixes #9660

gajim/application.py

@@ -379,6 +379,7 @@ class GajimApplication(Gtk.Application):
         act = Gio.SimpleAction.new_stateful(
             'agent', None,
             GLib.Variant.new_boolean(app.config.get('use_gpg_agent')))
+        act.connect('change-state', app_actions.on_use_pgp_agent)
         self.add_action(act)
 
         # General Actions