Increase dependencies version

- Add support `activesupport 5.1`
- Add support `actionpack 5.1`

telegram-bot.gemspec

@@ -20,8 +20,8 @@ Gem::Specification.new do |spec|
 
   spec.required_ruby_version = '~> 2.0'
 
-  spec.add_dependency 'activesupport', '>= 4.0', '< 5.1'
-  spec.add_dependency 'actionpack', '>= 4.0', '< 5.1'
+  spec.add_dependency 'activesupport', '>= 4.0', '<= 5.1'
+  spec.add_dependency 'actionpack', '>= 4.0', '<= 5.1'
   spec.add_dependency 'httpclient', '~> 2.7'
   spec.add_development_dependency 'bundler', '~> 1.11'
   spec.add_development_dependency 'rake', '~> 10.0'