The current version is 004. It was issued on 16th January 2023.
The XSD of this latest version can be found at http://ddex.net/xml/allowed-value-sets/allowed-value-sets.xsd.
The data dictionary edition for these AVSs is available here.
Older AVS XSDs can be accessed from http://ddex.net/xml/allowed-value-sets/allowed-value-sets_xxx.xsd with xxx being the zero padded version number. This only applies for XSDs that were published from 2021 onwards.
Changes are detailed here.