Suppress new RuboCop offenses

This commit suppresses the following new RuboCop offenses:

```console
$ bundle exec rubocop
(snip)

lib/rubocop/cop/performance/sum.rb:162:41: W: [Correctable] Lint/SafeNavigationConsistency: Use . instead of unnecessary &..
          receiver&.literal? && receiver&.array_type?
                                        ^^

118 files inspected, 1 offense detected, 1 offense autocorrectable
RuboCop failed!
```

lib/rubocop/cop/performance/sum.rb

@@ -159,7 +159,7 @@ def empty_array_literal?(node)
 
         def array_literal?(node)
           receiver = node.children.first
-          receiver&.literal? && receiver&.array_type?
+          receiver&.literal? && receiver.array_type?
         end
 
         def autocorrect(corrector, init, range)