Limit scikit-learn version to <0.23

Author: PrimozGodec

requirements-core.txt

@@ -1,7 +1,7 @@
 pip>=9.0
 numpy>=1.16.0
 scipy>=0.16.1
-scikit-learn>=0.22.0
+scikit-learn>=0.22.0,<0.23  # TODO: release when fixed: https://github.com/scikit-learn/scikit-learn/issues/17208
 bottleneck>=1.0.0
 # Reading Excel files
 xlrd>=0.9.2