style: target Ruby 2.4

DirtyF · DirtyF · commit b1c94e517b46 · 2020-06-24T10:35:04.000+02:00
diff --git a/.rubocop.yml b/.rubocop.yml
@@ -4,7 +4,7 @@ inherit_gem:
   rubocop-jekyll: .rubocop.yml
 
 AllCops:
-  TargetRubyVersion: 2.3
+  TargetRubyVersion: 2.4
   Include:
     - lib/**/*.rb
 
