Check if dependencies is installed in right version when running models

[AmaliePauli]

Based on issue #62 and #57 and it might be nice to a check when running the model to see if the right dependencies is installed, and otherwise send warning to what is needed.

[JensMadsen]

To start with perhaps add instruction in the README.md in line with:

To install the required dependencies:

• initiate a virtual environment: python -m venv venv
• activate: source venv/bin/activate
• install dependencies: pip install -r requirements.txt
• have fun

Perhaps using pip-compile would ease maintenance of dependencies? if you think so I gladly add that bit in a pull request.