docs: add note about Jest incompatibility to UPGRADING

[matthewmayer]

ref #3606

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.96%. Comparing base (51943ae) to head (a99e384).
⚠️ Report is 1 commits behind head on next.

Additional details and impacted files

@@           Coverage Diff           @@
##             next    #3609   +/-   ##
=======================================
  Coverage   99.96%   99.96%           
=======================================
  Files        2894     2894           
  Lines      222385   222385           
  Branches      928      929    +1     
=======================================
  Hits       222318   222318           
  Misses         67       67           

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