Add 8.1.3 changelog entry from stable branch

[alchemycms-bot]

Syncs changelog entry from stable branch release to main.

This ensures tools like Dependabot can see the changelog for this release.

This PR was automatically created by the post-release workflow.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.46%. Comparing base (688ae4c) to head (7650d90).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3692   +/-   ##
=======================================
  Coverage   97.46%   97.46%           
=======================================
  Files         314      314           
  Lines        8288     8288           
=======================================
  Hits         8078     8078           
  Misses        210      210           

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