changelog tweak

Author: nicolaskruchten

CHANGELOG.md

@@ -5,7 +5,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 ## [5.2.2] - ???
 
 ### Fixed
-  - Fixed error when using the orjson engine with non-string keys  
+  - Fixed error when using the orjson engine with non-string keys [#3351](https://github.com/plotly/plotly.py/pull/3351)
 
 ## [5.2.1] - 2021-08-13