Update changelog

CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+
+### Fixed
+
+- Fixed an issue with the currency conversion in the portfolio calculations
+
 ## 1.31.0 - 01.08.2021
 
 ### Added
@@ -13,7 +19,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
-- Refactored the core engine for the calculations
+- Refactored the core engine for the portfolio calculations
+- Improved the performance of the portfolio calculations
 
 ## 1.30.0 - 31.07.2021