installdeps: use confnew to workaround upgrade

scripts/installdeps.sh

@@ -3,7 +3,10 @@ set -eux
 cd "$(dirname ${BASH_SOURCE:0})/.."
 
 apt-get update
-DEBIAN_FRONTEND=noninteractive apt-get -o APT::Get::Always-Include-Phased-Updates=true -y dist-upgrade
+DEBIAN_FRONTEND=noninteractive apt-get \
+    -o Dpkg::Options::=--force-confnew \
+    -o APT::Get::Always-Include-Phased-Updates=true \
+    -y dist-upgrade
 mkdir -p /etc/systemd/system/zfs-mount.service.d/
 cat >/etc/systemd/system/zfs-mount.service.d/override.conf <<EOF
 [Unit]