docs: prepare CHANGELOG for v1.5.0 release

Author: tphakala

CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [1.5.0] - 2026-07-17
+
 ### Added
 
 - `Latency()` on `SimpleResampler` and `SimpleResamplerFloat32`, returning the
@@ -130,7 +132,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   design, quality presets, multi-channel and streaming support, validated against
   libsoxr.
 
-[Unreleased]: https://github.com/tphakala/go-audio-resampler/compare/v1.4.0...HEAD
+[Unreleased]: https://github.com/tphakala/go-audio-resampler/compare/v1.5.0...HEAD
+[1.5.0]: https://github.com/tphakala/go-audio-resampler/compare/v1.4.0...v1.5.0
 [1.4.0]: https://github.com/tphakala/go-audio-resampler/compare/v1.3.0...v1.4.0
 [1.3.0]: https://github.com/tphakala/go-audio-resampler/compare/v1.2.0...v1.3.0
 [1.2.0]: https://github.com/tphakala/go-audio-resampler/compare/v1.1.0...v1.2.0