Even if your postinst does not involve debconf, you currently need to make sure it loads one of the debconf libraries. This will be changed in the future.
The tag is present in Lintian version
That is the most recent version we know about.
We use semantic versions.
The patch number is a commit step indicator relative to the
release tag in our Git
You can find the detection logic for this version at commit fac7222. For merge requests, please use the latest version in the Lintian check debian/debconf.