These days it is strongly recommended that Python packages are properly type annotated so that static type checkers such as mypy can catch bugs at compile time. However it is virtually impossible to work with type annotations in Python <= 3.6 - even if they are not checked.

For example the crucial from __future__ import annotations which makes it possible to use forward references in type annotations only exists in Python >= 3.7. So I believe it is time to move on, and raise the minimal required Python version in the worker.