.rubocop.yml in postman_mta-0.1.9 vs .rubocop.yml in postman_mta-0.2.0

- old
+ new

@@ -1,8 +1,8 @@
 AllCops:
-  TargetRubyVersion: 2.3
+  TargetRubyVersion: 2.4
 
-  Excludes:
+  Exclude:
     - "Guardfile"
     - "Rakefile"
     - "bin/**/*"
     - "spec/dummy/**/*"
 