fix(python): Normalize by default in Series.entropy like Expr.entropy does

[orlp]

@stinodego Theoretically backwards-incompatible, but I consider it a bug that the Series method did something different than the Expr method. However, in any sensible use-case of Series.entropy the probabilities would have already summed to 1, meaning that turning on normalize shouldn't actually change behavior for users.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.85%. Comparing base (a5dc30d) to head (7b8723b).
Report is 23 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #18493   +/-   ##
=======================================
  Coverage   79.84%   79.85%           
=======================================
  Files        1501     1501           
  Lines      202032   202032           
  Branches     2868     2868           
=======================================
+ Hits       161309   161328   +19     
+ Misses      40176    40157   -19     
  Partials      547      547           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[ritchie46]

Given the inconsistency bug and that that proper usage would not break any code, I will merge this.