Update evaluation.py MRR metrics as previous metrics is Wrong

[Yazooliu]

I updated the MRR metrics in evaluation.py
and this PR update is
related to issue: 119

please check and send me reponse, thanks

Yazooliu
BR

[CLAassistant]

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[Yazooliu]

please check and approve.

[Yazooliu]

seems nobody maintenance for this ? @CLAassistant @ @nomagick @ZeyuChen @llxxxll
please correct me if i mentioned the wrong person. thanks.