Ignoring rubocop rules for Ruby 3.

.rubocop.yml

@@ -3,6 +3,7 @@ inherit_from: .rubocop_todo.yml
 
 # Apply rule to all cops
 AllCops:
+  TargetRubyVersion: 2.4
   Include:
     - '**/Rakefile'
     - '**/config.ru'

.rubocop_todo.yml

@@ -714,3 +714,12 @@ Style/TrailingCommaInLiteral:
     - 'Guardfile'
     - 'db/migrate/20140701123203_add_events_per_week_to_conference.rb'
     - 'spec/models/conference_spec.rb'
+
+
+# for ruby 3.0
+Style/FrozenStringLiteralComment:
+  Enabled: false
+Style/NumericPredicate:
+  Enabled: false
+Style/SafeNavigation:
+  Enabled: false