build(deps): bump rack from 2.2.3.1 to 2.2.6.4

Bumps [rack](https://github.com/rack/rack) from 2.2.3.1 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@2.2.3.1...v2.2.6.4)

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

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

Gemfile

@@ -7,4 +7,4 @@ gem 'tzinfo-data', platforms: [:mswin, :mingw, :jruby]
 gem 'wdm', '~> 0.1', platforms: [:mswin, :mingw]
 gem 'redcarpet', '3.5.1'
 gem 'pry'
-gem 'rack', '~> 2.2.3.1'
+gem 'rack', '~> 2.2.6.4'

Gemfile.lock

@@ -97,7 +97,7 @@ GEM
       coderay (~> 1.1)
       method_source (~> 1.0)
     public_suffix (5.0.0)
-    rack (2.2.3.1)
+    rack (2.2.6.4)
     rack-livereload (0.3.17)
       rack
     rb-fsevent (0.11.1)
@@ -128,7 +128,7 @@ DEPENDENCIES
   middleman-autoprefixer (~> 3.0.0)
   middleman-livereload (= 3.4.7)
   pry
-  rack (~> 2.2.3.1)
+  rack (~> 2.2.6.4)
   redcarpet (= 3.5.1)
   tzinfo-data
   wdm (~> 0.1)