Bump rack from 2.2.6.4 to 2.2.8.1

Bumps [rack](https://github.com/rack/rack) from 2.2.6.4 to 2.2.8.1.
- [Release notes](https://github.com/rack/rack/releases)
- [Changelog](https://github.com/rack/rack/blob/main/CHANGELOG.md)
- [Commits](rack/rack@v2.2.6.4...v2.2.8.1)

---
updated-dependencies:
- dependency-name: rack
  dependency-type: indirect
...

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

Gemfile.lock

@@ -305,7 +305,7 @@ GEM
     psych (3.3.3)
     public_suffix (5.0.1)
     racc (1.7.1)
-    rack (2.2.6.4)
+    rack (2.2.8.1)
     rack-attack (6.7.0)
       rack (>= 1.0, < 4)
     rack-piwik (0.3.0)