The --force flag of dpkg-statoverride has been deprecated (apparently starting
with the dpkg version in Debian buster). It offers --force-all as q quick fix,
but the usage in the Debian postinst script is probably covered by
--force-statoverride-add.

Fixes: #8391

Signed-off-by: Jörg Behrmann <behrmann@physik.fu-berlin.de>