Change dpkg-statoverride to use --force-statoverride-add (#13638)

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>

debian/changelog

@@ -3,6 +3,7 @@ matrix-synapse-py3 (1.66.0~rc2+nmu1) UNRELEASED; urgency=medium
   * Update debhelper to compatibility level 12.
   * Drop the preinst script stopping synapse.
   * Allocate a group for the system user.
+  * Change dpkg-statoverride to --force-statoverride-add.
 
  -- Jörg Behrmann <behrmann@physik.fu-berlin.de>  Tue, 23 Aug 2022 17:17:00 +0100
 

debian/matrix-synapse-py3.postinst

@@ -45,7 +45,7 @@ EOF
 
     for DIR in /var/lib/matrix-synapse /var/log/matrix-synapse /etc/matrix-synapse; do
       if ! dpkg-statoverride --list --quiet $DIR >/dev/null; then
-        dpkg-statoverride --force --quiet --update --add $USER "$(id -gn $USER)" 0755 $DIR
+        dpkg-statoverride --force-statoverride-add --quiet --update --add $USER "$(id -gn $USER)" 0755 $DIR
       fi
     done