disable 'update popup'

* see https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=943668

busunit/scripts/start-kiosk.sh

@@ -61,6 +61,7 @@ echo "XAUTHORITY=$XAUTHORITY" >> /tmp/kiosk.info
   --incognito \
   --disable-pinch \
   --overscroll-history-navigation=0 \
+  --disable-component-update \
   --disable-gpu \
   --kiosk \
   'http://localhost:60535'