Update changelog

Author: S7evinK

CHANGES.md

@@ -1,18 +1,15 @@
 # Synapse 1.121.0 (2024-12-11)
 
+This release contains the security fixes from [v1.120.2](https://github.com/element-hq/synapse/releases/tag/v1.120.2).
+
 ### Internal Changes
 
 - Fix release process to not create duplicate releases. ([\#18025](https://github.com/element-hq/synapse/issues/18025))
 
 
 
-
 # Synapse 1.121.0rc1 (2024-12-04)
 
-This release candidate contains the security fixes from [v1.120.2](https://github.com/element-hq/synapse/releases/tag/v1.120.2).
-
-New changes listed below.
-
 ### Features
 
 - Support for [MSC4190](https://github.com/matrix-org/matrix-spec-proposals/pull/4190): device management for Application Services. ([\#17705](https://github.com/element-hq/synapse/issues/17705))