Fix hooks

[Alexander-Dubrawski]

Somehow the hooks are not happy again. There are quite a few files where I needed to run the hooks on. I also changed:

• the python version for the hooks to python3.8 .
• I removed isort because it behaves (sorts differently) on Mac OSX and Linux. As a result of that is would be impossible to develop in both platforms.
• I also changed the action command to use https://github.com/pre-commit/action . So we get a much more helpful message is one hook fails.

ToDo:

• [x] write a wiki that explains pipenv  

  • [x] What to consider if a package is installed/uninstalled (update requirements with pipenv run pipenv_to_requirements (https://github.com/gsemet/pipenv-to-requirements))
  • [x] Why and when packages are updated (https://pipenv-fork.readthedocs.io/en/latest/basics.html)
  • [x] Explain dangerous behavior: If I install a new package on branch A (it seems that all packages are updated) the Pipefile.lockis updated. If I change to branch B my installation of the packages is not consistent with the Pipefile.lock file on branch B. As a resault the github action can fail.

• [x] Set a fix package versions in Pipfile

[Bensk1]

Lots of formatting changes, right?