[Request] Remove STIX1 support

[ostefano]

All stix1 packages (like mixbox and others) haven't been updated for the past 4/6 years.
This is an issue as newer versions of Python 3.12 have been deprecating packages (like distutils required by mixbox).

Would it make sense to remove the dependency to https://github.com/oasis-open/cti-stix-elevator (or split the packages) if possible?