Update dependency rack to v3

Author: renovate[bot]

Gemfile

@@ -6,7 +6,7 @@ gem 'multipart-post', '~> 2.4.1', require: false
 
 group :development, :test do
   # ref: http://docs.rubocop.org/en/latest/installation/
-  gem 'rack', '~> 2.2'
+  gem 'rack', '~> 3.0'
   gem 'rubocop', '~> 1.75.0', require: false
   gem 'webrick', '~> 1.9.1'
   gem 'yard', '~> 0.9.20'

Gemfile.lock

@@ -27,7 +27,7 @@ GEM
     prism (1.4.0)
     public_suffix (6.0.1)
     racc (1.8.1)
-    rack (2.2.13)
+    rack (3.1.12)
     rainbow (3.1.1)
     rake (13.2.1)
     regexp_parser (2.10.0)
@@ -79,7 +79,7 @@ DEPENDENCIES
   addressable (~> 2.3)
   line-bot-api!
   multipart-post (~> 2.4.1)
-  rack (~> 2.2)
+  rack (~> 3.0)
   rake (~> 13.0)
   rspec (~> 3.13.0)
   rubocop (~> 1.75.0)