Check if the dev environment does use the right files

[hf-krechan]

This repository is a python package.
During the development, the unittest and development tools (linter and debugger) should use the latest and greatest version of this package which lives in the ./src directory.
But at the moment there is also in .tox/dev/libs/ the ahbicht package, which could lead to very strange and misleading errors.
Therefore we have to check the tox.ini file which defines the environment setups.