The antora.yml file references a number of version-specific variables such as:

debezium-dev-version: '1.3'
install-version: '1.2'

which are no longer references anymore outside of some placeholders in install.adoc and even those placeholders aren't used. These can likely be removed entirely.

Additionally the variable

debezium-docker-label: '1.3'

can likely be resolved directly from debezium-version if Antora supports a way to parse the value and return the first major/minor version parts.