23/06/2022: Version 3.6.0 is on the way! Now we directly update the code on chX branches, please periodically check if there are any updates.

I think it's because the current version of scikit-learn 0.23.0 has removed linear_assignment_. I ran 'pip3 install scikit-learn==0.22.2' and I was able to run the demo after that.