Fix typo in updaterequireddialog.ui

Change-Id: I952486625daea6ed995b1e654d810585cce2c8c2
Reviewed-on: https://gerrit.libreoffice.org/12973
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>