Use cdebootstrap to workaround debootstrap bug (#598080).

auto/config

@@ -18,6 +18,7 @@ $RUN_LH_CONFIG \
    --binary-images iso-hybrid \
    --isohybrid-options "$AMNESIA_ISOHYBRID_OPTS" \
    --bootappend-live "${AMNESIA_APPEND}" \
+   --bootstrap "cdebootstrap" \
    --archive-areas "main contrib non-free" \
    --iso-application="The Amnesic Incognito Live System" \
    --iso-publisher="https://amnesia.boum.org/" \