update changelog

Author: alexbourret

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## [Version 1.3.1](https://github.com/dataiku/dss-plugin-pi-server/releases/tag/v1.3.1) - Bugfix release - 2025-05-24
+
+- Fix the mix mode interpolation type in Transpose & Synchronise (the Step value was inverted)
+
 ## [Version 1.3.0](https://github.com/dataiku/dss-plugin-pi-server/releases/tag/v1.3.0) - Feature and bug release - 2025-05-23
 
 - Accept timezone in datetime inputs