Add Pureos suites byzantium and crimson to debootstrap

PureOS as a downstream distribution of Debian has created two new suites, byzantium (follows bullseye, already created long ago) and crimson recently that will follow bookworm.

This MR is about adding support to dbootstrap so creating e.g. chroots of the new suites in PureOS can be done easily without using the SCRIPT option manually.

Note: The suite byzantium is also addressed within MR !60 (closed) .