`pip install` in Dockerfiles should specify the package versions
I was trying to find out which mypy version is used in the CI (in the paperwork image), but I see that none of the Dockerfiles specifies the version of any package that is installed. I think this is very dangerous, as it is basically impossible to reproduce the Docker image that is currently in use from scratch. If this image is ever rebuilt all the tests will most likely fail because mypy changes behavior occasionally with new versions. Similar things apply for all other pip install
commands in the Dockerfiles.