chore: Add external contributor to CHANGELOG.md (#16338)

This PR adds the external contributor to the CHANGELOG.md file, so that
they are credited for their contribution. See #14629

Co-authored-by: mydea <[email protected]>

Author: HazAT

CHANGELOG.md

@@ -10,6 +10,8 @@
 
 - "You miss 100 percent of the chances you don't take. — Wayne Gretzky" — Michael Scott
 
+Work in this release was contributed by @phthhieu. Thank you for your contribution!
+
 ## 9.20.0
 
 ### Important changes