Update CHANGELOG.rst

Co-authored-by: Hugo van Kemenade <[email protected]>

Author: JulienPalard

CHANGELOG.rst

@@ -13,6 +13,8 @@ Changelog
   Contributed by Adam Turner
 - Override font for ``.sig`` for consistency with other code blocks. (#121)
   Contributed by Chris Warrick
+- Dark mode: add class to invert image brightness. (#128)
+  Contributed by Hugo van Kemenade
 
 
 `2023.3.1 <https://github.com/python/python-docs-theme/releases/tag/v2023.3.1>`_