Bump rack from 3.0.8 to 3.0.9.1

Bumps [rack](https://github.com/rack/rack) from 3.0.8 to 3.0.9.1.
- [Release notes](https://github.com/rack/rack/releases)
- [Changelog](https://github.com/rack/rack/blob/main/CHANGELOG.md)
- [Commits](rack/rack@v3.0.8...v3.0.9.1)

---
updated-dependencies:
- dependency-name: rack
  dependency-type: direct:production
...

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

Gemfile.lock

@@ -41,7 +41,7 @@ GEM
     polyphony (1.4)
     qeweney (0.18)
       escape_utils (~> 1.2.1)
-    rack (3.0.8)
+    rack (3.0.9.1)
     rake (13.0.6)
     ruby2_keywords (0.0.5)
     simplecov (0.22.0)