docs: Update changelog for 4.0 release

[jumpingliu]

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• I am not introducing a breaking change (if you are, flag in conventional commit message with BREAKING CHANGE: describing the break)
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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 32.27%. Comparing base (30af94e) to head (b6514ed).

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Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1693   +/-   ##
=======================================
  Coverage   32.27%   32.27%           
=======================================
  Files          51       51           
  Lines        4905     4905           
=======================================
  Hits         1583     1583           
  Misses       3184     3184           
  Partials      138      138           

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