Fix RuboCop violations.

reitermarkus · reitermarkus · commit ce1b142e8bef · 2020-08-31T03:44:09.000+02:00
diff --git a/Gemfile b/Gemfile
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 source "https://rubygems.org"
 
 group :test do
diff --git a/spec/stub/exceptions.rb b/spec/stub/exceptions.rb
@@ -1,2 +1,4 @@
+# frozen_string_literal: true
+
 class UsageError < RuntimeError
 end
