Add changelog for 3.2.3

Author: consideRatio

docs/source/changelog.md

@@ -98,6 +98,10 @@ See [our definition of contributors](https://github-activity.readthedocs.io/en/l
 
 ## 3.2
 
+### 3.2.3 - 2024-03-13
+
+This is a security release for [GHSA-w3vc-fx9p-wp4v](https://github.com/jupyterhub/jupyter-server-proxy/security/advisories/GHSA-w3vc-fx9p-wp4v).
+
 ### 3.2.2 - 2022-09-08
 
 #### Bugs fixed