update CHANGELOG.md and CONTRIBUTORS.md

Author: chthollyphile

CHANGELOG.md

@@ -30,6 +30,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Adds a `case_sensitive` parameter to `prompt.Prompt`. This determines if the
   response is treated as case-sensitive. Defaults to `True`.
+- Add a new `column` object `IterationSpeedColumn`. https://github.com/Textualize/rich/pull/3332
 
 ## [13.7.1] - 2024-02-28
 

CONTRIBUTORS.md

@@ -85,3 +85,4 @@ The following people have contributed to the development of Rich:
 - [Pierro](https://github.com/xpierroz)
 - [Bernhard Wagner](https://github.com/bwagner)
 - [Aaron Beaudoin](https://github.com/AaronBeaudoin)
+- [chthollyphile](https://github.com/chthollyphile)