Update RuboCop to 0.56.0 (#1227)

Also fixes new offenses

Gemfile.lock

@@ -23,7 +23,7 @@ GEM
     powerpack (0.1.1)
     rainbow (3.0.0)
     rake (12.3.0)
-    rubocop (0.55.0)
+    rubocop (0.56.0)
       parallel (~> 1.10)
       parser (>= 2.5)
       powerpack (~> 0.1)

lib/faker/star_wars.rb

@@ -74,7 +74,7 @@ def quote(character = nil)
             character = k.to_s if v.include?(character)
           end
 
-          unless quoted_characters.keys.include?(character.to_sym)
+          unless quoted_characters.key?(character.to_sym)
             raise ArgumentError, "Character for quotes can be left blank or #{quoted_characters.keys.join(', ')}"
           end
         end

lib/helpers/unique_generator.rb

@@ -6,7 +6,7 @@ def initialize(generator, max_retries)
       @previous_results = Hash.new { |hash, key| hash[key] = Set.new }
     end
 
-    # rubocop:disable Style/MethodMissing
+    # rubocop:disable Style/MethodMissingSuper
     def method_missing(name, *arguments)
       @max_retries.times do
         result = @generator.public_send(name, *arguments)
@@ -19,7 +19,7 @@ def method_missing(name, *arguments)
 
       raise RetryLimitExceeded
     end
-    # rubocop:enable Style/MethodMissing
+    # rubocop:enable Style/MethodMissingSuper
 
     def respond_to_missing?(method_name, include_private = false)
       method_name.to_s.start_with?('faker_') || super