get rid of warnings in the datalab quickstart tutorial

[coding-famer]

fixes #1053

just increase the number of samples of the rare class, but it is still a relatively small number.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 96.25%. Comparing base (b751269) to head (e19312f).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1083      +/-   ##
==========================================
+ Coverage   96.20%   96.25%   +0.05%     
==========================================
  Files          75       75              
  Lines        5870     5870              
  Branches     1046     1046              
==========================================
+ Hits         5647     5650       +3     
+ Misses        132      130       -2     
+ Partials       91       90       -1     

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