Update changelog according to new release (#449)

CHANGELOG.md

@@ -4,7 +4,7 @@ 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] - YYYY-MM-DD
+## [0.1.3] - 2020-09-24
 ### Added
 - [#417](https://github.com/equinor/webviz-subsurface/pull/417) - Added an optional argument `--testdata-folder` to `pytest`, can be used when [test data](https://github.com/equinor/webviz-subsurface-testdata) is in non-default location.
 - [#422](https://github.com/equinor/webviz-subsurface/pull/422) - `HistoryMatch` plugin now