Bump rack from 2.2.6.3 to 2.2.6.4

Bumps [rack](https://github.com/rack/rack) from 2.2.6.3 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@v2.2.6.3...v2.2.6.4)

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

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

Author: dependabot[bot]

Gemfile.lock

@@ -135,7 +135,7 @@ GEM
       racc (~> 1.4)
     public_suffix (4.0.6)
     racc (1.6.1)
-    rack (2.2.6.3)
+    rack (2.2.6.4)
     rack-accept (0.4.5)
       rack (>= 0.4)
     rack-cors (1.1.1)