Fix typo in plotly_colorscale

[simsurace]

Fixes #5016 on master (v1 bugfix).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.76%. Comparing base (fa65e7d) to head (a1a953e).
Report is 30 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5018      +/-   ##
==========================================
- Coverage   89.77%   89.76%   -0.01%     
==========================================
  Files          40       40              
  Lines        8780     8797      +17     
==========================================
+ Hits         7882     7897      +15     
- Misses        898      900       +2     

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