[pkg] Remove build dependency on dh-systemd As suggested by Lintian, remove build dependency on obsolete package dh-systemd. Instead, specify a more precise version of debhelper 9 that added support for systemd.

#!/bin/sh -e

if [ "$1" = "purge" ] ; then
        rm -rf /etc/cubicweb.d/
        rm -rf /var/log/cubicweb/
        rm -rf /var/lib/cubicweb/
fi

#DEBHELPER#
 
exit 0