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: direct:production
...

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

Gemfile.lock

@@ -321,7 +321,7 @@ GEM
  puma (5.6.4)
  nio4r (~> 2.0)
  racc (1.6.2)
- rack (2.2.6.3)
+ rack (2.2.6.4)
  rack-oauth2 (1.19.0)
  activesupport
  attr_required