[Release] Keep a changelog: version 3.2.0

Author: okuramasafumi

CHANGELOG.md

@@ -6,6 +6,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [3.2.0] 2024-06-21
+
+### Added
+
+- Rails controller integration [#370](https://github.com/okuramasafumi/alba/pull/370)
+- Modification API: `transform_keys!` [#372](https://github.com/okuramasafumi/alba/pull/372)
+
 ## [3.1.0] 2024-03-23
 
 ### Added