fix: change changelog section

Author: Monska85

CHANGELOG.md

@@ -12,7 +12,7 @@ to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 [Compare with previous version](https://github.com/sparkfabrik/terraform-gitlab-kubernetes-gitlab-agent/compare/0.5.0...0.6.0)
 
-### Added
+### Changed
 
 - Upgrade the default Helm chart to version `2.6.2`.