Ensure that bash is used with the tox users script

src/freedombone-image-customise

 EOF
     chroot "$rootdir" chown $MY_USERNAME:$MY_USERNAME /usr/bin/list-tox-users
     chroot "$rootdir" chmod +x /usr/bin/list-tox-users
-    echo "* *       * * *   $MY_USERNAME    /usr/bin/list-tox-users > /dev/null" >> $rootdir/etc/crontab
+    echo "* *       * * *   $MY_USERNAME    bash -c /usr/bin/list-tox-users > /dev/null" >> $rootdir/etc/crontab
 
     if [[ $VARIANT != "usb" ]]; then
         # log in automatically