Add changelog entry

Author: robertoffmoura

CHANGELOG.md

@@ -10,6 +10,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
 ### Fixed
 - Fix `mpl_to_plotly` not setting `paper_bgcolor` and `plot_bgcolor` from the matplotlib figure and axes backgrounds, so converted figures match the source figure's background colors [[#5285](https://github.com/plotly/plotly.py/pull/5285)], with thanks to @robertoffmoura for the contribution!
+- Fix `mpl_to_plotly` drawing step plots with diagonal lines instead of vertical/horizontal step segments by mapping matplotlib step drawstyles (`steps-pre`, `steps-post`, `steps-mid`) to plotly line shapes [[#5697](https://github.com/plotly/plotly.py/pull/5697)], with thanks to @robertoffmoura for the contribution!
 
 ## [7.0.0] - 2026-08-25