Prepare release v0.3.1

## heroku/go

- Added go1.21.10 (linux-amd64), go1.21.10 (linux-arm64), go1.22.3 (linux-amd64), go1.22.3 (linux-arm64).

buildpacks/go/CHANGELOG.md

@@ -7,7 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [0.3.1] - 2024-05-07
+
 - Added go1.21.10 (linux-amd64), go1.21.10 (linux-arm64), go1.22.3 (linux-amd64), go1.22.3 (linux-arm64).
+
 ## [0.3.0] - 2024-05-02
 
 ### Added
@@ -153,7 +156,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Initial implementation using libcnb.rs. ([#1](https://github.com/heroku/buildpacks-go/pull/1))
 
-[unreleased]: https://github.com/heroku/buildpacks-go/compare/v0.3.0...HEAD
+[unreleased]: https://github.com/heroku/buildpacks-go/compare/v0.3.1...HEAD
+[0.3.1]: https://github.com/heroku/buildpacks-go/compare/v0.3.0...v0.3.1
 [0.3.0]: https://github.com/heroku/buildpacks-go/compare/v0.2.1...v0.3.0
 [0.2.1]: https://github.com/heroku/buildpacks-go/compare/v0.2.0...v0.2.1
 [0.2.0]: https://github.com/heroku/buildpacks-go/compare/v0.1.16...v0.2.0

buildpacks/go/buildpack.toml

@@ -2,7 +2,7 @@ api = "0.10"
 
 [buildpack]
 id = "heroku/go"
-version = "0.3.0"
+version = "0.3.1"
 name = "Heroku Go"
 homepage = "https://github.com/heroku/buildpacks-go"
 description = "Heroku's buildpack for Go applications."