Bump rack from 2.2.6.3 to 2.2.6.4 (#131)

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]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

Gemfile.lock

@@ -143,7 +143,7 @@ GEM
     ood_support (0.0.3)
     public_suffix (5.0.1)
     racc (1.6.2)
-    rack (2.2.6.3)
+    rack (2.2.6.4)
     rack-test (2.0.2)
       rack (>= 1.3)
     rails (6.0.6.1)