Bump rack from 2.2.3 to 2.2.3.1

Bumps [rack](https://github.com/rack/rack) from 2.2.3 to 2.2.3.1.
- [Release notes](https://github.com/rack/rack/releases)
- [Changelog](https://github.com/rack/rack/blob/main/CHANGELOG.md)
- [Commits](rack/rack@2.2.3...2.2.3.1)

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

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

Author: dependabot[bot]

Gemfile.lock

@@ -4,7 +4,7 @@ GEM
     multi_json (1.15.0)
     mustermann (1.1.1)
       ruby2_keywords (~> 0.0.1)
-    rack (2.2.3)
+    rack (2.2.3.1)
     rack-protection (2.2.0)
       rack
     ruby2_keywords (0.0.5)