Update CHANGELOG

Author: ossus-lib

CHANGELOG.md

@@ -4,6 +4,13 @@ Changelog
 Version numbering represents the Swift version, plus a running number representing updates, fixes and new features at the same time.
 You can also refer to commit logs to get details on what was implemented, fixed and improved.
 
+### 5.3.0
+
+- Fix `ASWebAuthenticationSession` implementation.  
+  [james-rantmedia](https://github.com/james-rantmedia)
+  [#327](https://github.com/p2/OAuth2/pull/327)
+- Various fixes and improvements.
+
 ### 5.2.0
 
 - Separate setting for `refresh_uri`.