Fix and update installation

[ClaraBuettner]

The current installation process is not working anymore and has several problems.

Both eTraGo and eDisGo have to be added in the installation requirements (after they have been released). As an intermediate solution, we could write in the instructions which branches of eTraGo and eDisGo have to be cloned and installed beforehand.

The Python version has to be adjusted to one that is compatible to eTraGo and eDisGo.

[ClaraBuettner]

We tried to create a Python3.10 venv and installed first eTraGo (version0.10.1) and eGo afterwards.
But this line creates problems during the installation with python3.10:

eGo/setup.py

Line 6 in dfab09e

from pip._internal.req import parse_requirements

When this line is commented, the installation runs through, but it could be wrong.

We have to check how we can fix that in a better way.