Bump rack from 3.1.8 to 3.1.9

Bumps [rack](https://github.com/rack/rack) from 3.1.8 to 3.1.9.
- [Release notes](https://github.com/rack/rack/releases)
- [Changelog](https://github.com/rack/rack/blob/main/CHANGELOG.md)
- [Commits](rack/rack@v3.1.8...v3.1.9)

---
updated-dependencies:
- dependency-name: rack
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Gemfile.lock

@@ -96,7 +96,7 @@ GEM
     public_suffix (6.0.1)
     raabro (1.4.0)
     racc (1.8.1)
-    rack (3.1.8)
+    rack (3.1.9)
     rackup (2.2.1)
       rack (>= 3)
     rainbow (3.1.1)