Bump rack from 2.2.7 to 2.2.8.1

Bumps [rack](https://github.com/rack/rack) from 2.2.7 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@v2.2.7...v2.2.8.1)

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

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

Gemfile.lock

@@ -116,7 +116,7 @@ GEM
       coderay (~> 1.1.0)
       method_source (~> 0.9.0)
     racc (1.7.1)
-    rack (2.2.7)
+    rack (2.2.8.1)
     rack-test (2.1.0)
       rack (>= 1.3)
     rails (6.1.7.6)