Update CHANGELOG.md

Author: evanglass

CHANGELOG.md

@@ -21,6 +21,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 * `selectize`, `remove_button`, and `options` parameters of `ui.input_select()` have been deprecated; use `ui.input_selectize()` instead. (Thanks, @ErdaradunGaztea!) (#1947)
 
+* Added `timeout_secs` parameter to `create_app_fixture` to allow testing apps with longer startup times. (#2033)
+
 ### Bug fixes
 
 * Fixed an issue with `ui.Chat()` sometimes wanting to scroll a parent element. (#1996)