chore(release): generate changelog for v0.4.0

CHANGELOG.md

@@ -2,6 +2,36 @@
 
 All notable changes to this project will be documented in this file.
 
+## [0.4.0] - 2023-12-26
+
+### Documentation
+
+- Updates and fixes
+
+### Features
+
+- Initial functions support in the query builder API
+- Initial impl of promql validation macro
+
+### Refactor
+
+- Remove an error variant that is never used
+
+### Miscellaneous Tasks
+
+- Generate changelog for v0.4.0
+- Bump version to 0.4.0
+
+## [0.3.1] - 2023-12-20
+
+### Bug Fixes
+
+- Correct Sealed trait's visibility
+
+### Miscellaneous Tasks
+
+- Bump version to 0.3.1
+
 ## [0.3.0] - 2023-12-19
 
 ### Bug Fixes