Bump rack from 2.2.6.2 to 2.2.6.4

Bumps [rack](https://github.com/rack/rack) from 2.2.6.2 to 2.2.6.4.
- [Release notes](https://github.com/rack/rack/releases)
- [Changelog](https://github.com/rack/rack/blob/main/CHANGELOG.md)
- [Commits](rack/rack@v2.2.6.2...v2.2.6.4)

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

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

Author: dependabot[bot]

Gemfile.lock

@@ -97,7 +97,7 @@ GEM
     parser (3.0.2.0)
       ast (~> 2.4.1)
     racc (1.6.2)
-    rack (2.2.6.2)
+    rack (2.2.6.4)
     rack-proxy (0.7.0)
       rack
     rack-test (1.1.0)