Currently we pin scikit-learn to 0.22, because the Gaussian process implementation of scikit-learn 0.23 introduced normalize_y with division by the standard deviation. That will cause problems, when all datapoints produced the same output.

See:
scikit-optimize/scikit-optimize#947
scikit-learn/scikit-learn#18371
scikit-learn/scikit-learn#18318
scikit-learn/scikit-learn#18388

To do

• Update scikit-learn to >=0.22,<0.24
• Update scikit-optimize to ^0.8
• Evaluate if tests need to be recalculated (likely) and update them