ref: Add external contributor to CHANGELOG.md (#13552)

This PR adds the external contributor to the CHANGELOG.md file, so that
they are credited for their contribution. See #13540

Author: github-actions[bot]

CHANGELOG.md

@@ -10,7 +10,7 @@
 
 - "You miss 100 percent of the chances you don't take. — Wayne Gretzky" — Michael Scott
 
-Work in this release was contributed by @leopoldkristjansson. Thank you for your contribution!
+Work in this release was contributed by @leopoldkristjansson and @mhuggins. Thank you for your contributions!
 
 ### Important Changes