.rubocop.yml in grumlin-0.13.1 vs .rubocop.yml in grumlin-0.14.0

- old
+ new

@@ -1,6 +1,6 @@
 AllCops:
-  TargetRubyVersion: 2.6
+  TargetRubyVersion: 2.7
   NewCops: enable
   SuggestExtensions: false
 
 require:
   - rubocop-performance