Bump rack from 2.2.3.1 to 2.2.8.1

Bumps [rack](https://github.com/rack/rack) from 2.2.3.1 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@2.2.3.1...v2.2.8.1)

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

Signed-off-by: dependabot[bot] <[email protected]>

Gemfile.lock

@@ -83,7 +83,7 @@ GEM
     parallel (1.21.0)
     phantomjs (2.1.1.0)
     public_suffix (4.0.6)
-    rack (2.2.3.1)
+    rack (2.2.8.1)
     rake (12.3.3)
     rb-fsevent (0.11.0)
     rb-inotify (0.10.1)