updates to changelog

Author: rishabhpoddar

CHANGELOG.md

@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [unreleased]
 
+## [0.13.1] - 2023-05-15
 ### Changes
 -   Made the access token string optional in the overrideable `get_session` function
 -   Moved checking if the access token is defined into the overrideable `get_session` function