all: Set changelog to v0.12.0

Author: KrishnaIyer

CHANGELOG.md

@@ -8,14 +8,22 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 
 ### Added
 
-- Support for ChirpStack v4.
-
 ### Changed
 
 ### Deprecated
 
 ### Removed
 
+### Fixed
+
+## [v0.12.0] (2024-03-13)
+
+### Added
+
+- Support for ChirpStack v4.
+
+### Removed
+
 - Support for ChirpStack v3. Use versions `0.11.x` for ChirpStack v3.
 
 ### Fixed