Add v0.6.0 to changelog

Quick follow up to #36 to add forgotten v0.6.0 banner to the changelog.

Author: brandur

CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [0.6.0] - 2025-11-20
+
 ### Added
 
 - Add `panictoerror` middleware that recovers panics and returns them as errors to middlewares up the stack. [PR #32](https://github.com/riverqueue/rivercontrib/pull/32).