CHANGELOG: add entry for patch 1249

Author: dannywillems

CHANGELOG.md

@@ -43,6 +43,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
+- **CI**: Generalized build jobs to support multiple platforms (Ubuntu 22.04,
+  Ubuntu 24.04, Ubuntu 24.04 ARM, macOS latest) and updated test execution to
+  ubuntu-latest ([#1249](https://github.com/o1-labs/openmina/pull/1249))
 - **Build System**: Enhanced Makefile with documentation-related targets and comprehensive formatting commands ([#1234](https://github.com/o1-labs/openmina/pull/1234))
 ### Fixed