The tag is present in Lintian version 2.109.24. That is the most recent version we know about.
This package appears to be the initial packaging of a new upstream software package (ie. it contains a single changelog entry). However, it ships the specified module for Python 2.
Python 2.x modules should not be packaged unless strictly necessary (such as being explicitly requested by an end-user or required as part of a dependency chain) as the 2.x series of Python is due for deprecation and will not be maintained by upstream past 2020 and will likely be dropped after the release of Debian "buster".
If upstream have not moved or have no intention to move to Python 3, please be certain that Debian would benefit from the inclusion, continued maintenance burden and (eventual) removal of this package before you upload.
This warning can be ignored if the package is not intended for Debian or if it is a split of an existing Debian package. This warning can also be ignored if viewed on https://lintian.debian.org/.
Please do not override this warning; rather, add a justification to your changelog entry; Lintian looks in this version's changelog entry for the specified package name or the phrase "Python 2 version" or similar. This will ensure that any rationale is preserved for posterity.