chore(deps-dev): bump rack-test

Bumps [rack-test](https://github.com/rack/rack-test) from 2.1.0 to 2.2.0.
- [Release notes](https://github.com/rack/rack-test/releases)
- [Changelog](https://github.com/rack/rack-test/blob/main/History.md)
- [Commits](rack/rack-test@v2.1.0...v2.2.0)

---
updated-dependencies:
- dependency-name: rack-test
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

buildpacks/buildpack-ruby/tests/ruby-sinatra/Gemfile.lock

@@ -16,7 +16,7 @@ GEM
       rack (>= 3.0.0, < 4)
     rack-session (2.0.0)
       rack (>= 3.0.0)
-    rack-test (2.1.0)
+    rack-test (2.2.0)
       rack (>= 1.3)
     rackup (2.2.1)
       rack (>= 3)