Update ruby version and upgrade rubocop accordingly

.rubocop.yml

@@ -15,3 +15,4 @@ SpaceAroundKeyword:
 
 AllCops:
   DisplayCopNames: true
+  TargetRubyVersion: 2.1

.ruby-version

@@ -1 +1 @@
-2.2.3
+2.5.0

.travis.yml

@@ -1,7 +1,7 @@
 language: ruby
 rvm:
-  - 2.2.3
   - rbx-2
+  - 2.5.0
   - ruby-head
 before_install:
   - gem update --system

lib/public_ip.rb

@@ -26,7 +26,7 @@ def get_ip(service: :random)
     end
   rescue Timeout::Error
     tries -= 1
-    retry if tries > 0 && service == :random
+    retry if tries.positive? && service == :random
 
     raise PublicIp::TimedOut, 'Took too long to get your public ip address, try with another service'
   end

public_ip.gemspec

@@ -25,16 +25,17 @@ Gem::Specification.new do |spec|
   spec.executables   = ['public_ip']
   spec.require_paths = ['lib']
 
-  spec.required_ruby_version = '>= 2.0'
+  spec.required_ruby_version = '>= 2.1'
 
   spec.add_dependency 'methadone', '~> 1.9.2'
   spec.add_dependency 'nokogiri', '~> 1.8.1'
 
+  spec.add_development_dependency 'aruba', '~> 0.11.2'
   spec.add_development_dependency 'bundler', '~> 1.10'
+  spec.add_development_dependency 'pry', '~> 0.10.3'
   spec.add_development_dependency 'rake', '~> 10.0'
   spec.add_development_dependency 'rspec', '~> 3.4'
-  spec.add_development_dependency 'rubocop', '~> 0.49.0'
-  spec.add_development_dependency 'pry', '~> 0.10.3'
+  spec.add_development_dependency 'rubocop', '~> 0.52.1'
   spec.add_development_dependency 'webmock', '~> 1.22.3'
-  spec.add_development_dependency 'aruba', '~> 0.11.2'
 end
+# rubocop:enable Metrics/BlockLength