Update CHANGELOG.md for MeteorScoreEvaluator bug fix

Co-authored-by: singankit <[email protected]>

Author: Copilot

sdk/evaluation/azure-ai-evaluation/CHANGELOG.md

@@ -1,5 +1,10 @@
 # Release History
 
+## 1.9.0 (Unreleased)
+
+### Bugs Fixed
+- Fixed MeteorScoreEvaluator and other threshold-based evaluators returning incorrect binary results due to integer conversion of decimal scores. Previously, decimal scores like 0.9375 were incorrectly converted to integers (0) before threshold comparison, causing them to fail even when above the threshold. [#41415](https://github.com/Azure/azure-sdk-for-python/issues/41415)
+
 ## 1.8.0 (2025-05-29)
 
 ### Features Added