Release v0.6.0 (#134)

This PR edits the CHANGELOG to mark the release of `v0.6.0`, which
bundles together changes that have accumulated over the past year.

Author: kmaziarz

CHANGELOG.md

@@ -7,6 +7,8 @@ and the project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 
+## [0.6.0] - 2025-09-23
+
 ### Changed
 
 - Drop support for Python 3.7 ([#113](https://github.com/microsoft/syntheseus/pull/113)) ([@kmaziarz])
@@ -124,13 +126,14 @@ and the project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.
 
 :seedling: Initial public release, containing several multi-step search algorithms and a minimal interface for single-step models.
 
-[Unreleased]: https://github.com/microsoft/syntheseus/compare/v0.5.0...HEAD
+[Unreleased]: https://github.com/microsoft/syntheseus/compare/v0.6.0...HEAD
 [0.1.0]: https://github.com/microsoft/syntheseus/releases/tag/v0.1.0
 [0.2.0]: https://github.com/microsoft/syntheseus/releases/tag/v0.2.0
 [0.3.0]: https://github.com/microsoft/syntheseus/releases/tag/v0.3.0
 [0.4.0]: https://github.com/microsoft/syntheseus/releases/tag/v0.4.0
 [0.4.1]: https://github.com/microsoft/syntheseus/releases/tag/v0.4.1
 [0.5.0]: https://github.com/microsoft/syntheseus/releases/tag/v0.5.0
+[0.6.0]: https://github.com/microsoft/syntheseus/releases/tag/v0.6.0
 
 [@austint]: https://github.com/AustinT
 [@kmaziarz]: https://github.com/kmaziarz