.rubocop.yml in keep_up-0.7.1 vs .rubocop.yml in keep_up-0.8.0

@@ -1,13 +1,14 @@
 inherit_from: .rubocop_todo.yml
 
 require:
   - rubocop-rspec
+  - rubocop-performance
 
 AllCops:
   Exclude:
     - 'tmp/**/*'
-  TargetRubyVersion: 2.3
+  TargetRubyVersion: 2.4
 
 # Dot at end of line makes it clearer that the line is not done
 Layout/DotPosition:
   EnforcedStyle: trailing