Prepare release v4.0.1

## heroku/ruby

### Fixed

- A bug introduced in 4.0.0 would result in incorrectly skipping running `bundle install` when the `Gemfile` or `Gemfile.lock` or environment variables had changed. The bug is now fixed. ([#364](#364))

buildpacks/ruby/CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [4.0.1] - 2024-12-11
+
 ### Fixed
 
 - A bug introduced in 4.0.0 would result in incorrectly skipping running `bundle install` when the `Gemfile` or `Gemfile.lock` or environment variables had changed. The bug is now fixed. ([#364](https://github.com/heroku/buildpacks-ruby/pull/364))
@@ -71,7 +73,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Initial version of Ruby buildpack in Rust (https://github.com/heroku/buildpacks-ruby/pull/93)
 - Version 2.0.0 for the first release is not a typo. There was an issue in pack where a builder with the same name and version number would reuse artifacts left on image from [prior runs which caused issues](https://github.com/buildpacks/pack/issues/1322#issuecomment-1038241038). There were prior releases of `heroku/ruby` CNB from different sources that triggered this problem. To ensure no one would encounter that issue we developed and released using a version we know has not been used before. Version 2.0 was the first major version without a prior release of `heroku/ruby` CNB from any source.
 
-[unreleased]: https://github.com/heroku/buildpacks-ruby/compare/v4.0.0...HEAD
+[unreleased]: https://github.com/heroku/buildpacks-ruby/compare/v4.0.1...HEAD
+[4.0.1]: https://github.com/heroku/buildpacks-ruby/compare/v4.0.0...v4.0.1
 [4.0.0]: https://github.com/heroku/buildpacks-ruby/compare/v3.0.0...v4.0.0
 [3.0.0]: https://github.com/heroku/buildpacks-ruby/compare/v2.1.3...v3.0.0
 [2.1.3]: https://github.com/heroku/buildpacks-ruby/compare/v2.1.2...v2.1.3

buildpacks/ruby/buildpack.toml

@@ -2,7 +2,7 @@ api = "0.10"
 
 [buildpack]
 id = "heroku/ruby"
-version = "4.0.0"
+version = "4.0.1"
 name = "Heroku Ruby"
 homepage = "https://github.com/heroku/buildpacks-ruby"
 description = "Heroku's buildpack for Ruby applications."