The specified Python-Version or Python3-Version field is used to specify the version(s) of Python the package supports. However, the associated Python version is satisfied by the current "oldstable" distribution of Debian and is therefore unnecessary.
Please remove or update the reference. If removing, please also check for the use of py3versions -r in debian/rules, and debian/tests/. Without an operative Python3-Version field py3versions will fall back to all supported versions which may not be appropriate.