python-debian has invalid version

Ubuntu: Ubuntu 20.04 (actually it's Linux Mint 20.1)
Package: python-debian 0.1.36ubuntu1

Python package version should correspond to PEP 440:
    https://www.python.org/dev/peps/pep-0440/#local-version-identifiers

It requires + sign before local version identifier, like:
    2.0.0+ubuntu0.20.4.4

So python-debian should have version like:
    0.1.36+ubuntu1

Actually if you'll launch pip list, you'll see:
    python-debian 0.1.36ubuntu1

Why does it matter:
    Some package managers, like Poetry, will fail parsing this version.
    I thought to fix Poetry, but don't think I should handle not PEP 440-compliant versions
    in PEP 440 version parser.

Notes:
    This only should apply to version, specified for pip - Python package manager, not Apt.
    Version in Apt may stay 0.1.36ubuntu1.

Corresponding issue for Poetry:
    https://github.com/python-poetry/poetry/issues/4022