whatsnew updates for v3.13.0

[bjlittle]

🚀 Pull Request

Description

Minor update to whatsnew for pending iris 3.13.0 release.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.93%. Comparing base (d6e487e) to head (0a64798).
⚠️ Report is 6 commits behind head on v3.13.x.

Additional details and impacted files

@@           Coverage Diff            @@
##           v3.13.x    #6616   +/-   ##
========================================
  Coverage    89.93%   89.93%           
========================================
  Files           91       91           
  Lines        24393    24393           
  Branches      4554     4554           
========================================
  Hits         21938    21938           
  Misses        1686     1686           
  Partials       769      769           

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