add task to kill systemd-timesyncd and enable chrony

....otherwise DietPi has issues if we ever want to use dietpi-software 
it seems

src/steps-config/100-chrony.sh

@@ -0,0 +1,3 @@
+#!/usr/bin/env bash
+
+queue_apt_install "chrony";

src/steps-postinstall/100-chrony.sh

@@ -0,0 +1,11 @@
+#!/usr/bin/env bash
+
+task_begin "Stopping systemd-timesyncd";
+systemctl stop systemd-timesyncd
+systemctl disable systemd-timesyncd
+systemctl mask systemd-timesyncd
+task_end 0;
+
+task_begin "Starting and enabling chrony";
+systemctl enable --now chrony
+task_end "$?";