Update Rack version to v2.0.8+

Author: ryokdy

aws-sessionstore-dynamodb.gemspec

@@ -17,6 +17,6 @@ Gem::Specification.new do |spec|
 
   spec.add_dependency 'aws-sdk-dynamodb', '~> 1', '>= 1.85.0'
   spec.add_dependency('actionpack', '>= 6.1')
-  spec.add_dependency 'rack', '~> 3'
+  spec.add_dependency 'rack', '>= 2.0.8', '< 4'
   spec.add_dependency 'rack-session', '>= 2.0.0'
 end