docs: Update changelog for 4.0 release

[jumpingliu]

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 42.95%. Comparing base (583c141) to head (ad703fb).

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Additional details and impacted files

@@           Coverage Diff           @@
##             main     #985   +/-   ##
=======================================
  Coverage   42.95%   42.95%           
=======================================
  Files         119      119           
  Lines        7205     7205           
=======================================
  Hits         3095     3095           
  Misses       3767     3767           
  Partials      343      343           

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