Merge pull request #160 from github/dependabot/bundler/rubocop-performance-1.21.0

Bump rubocop-performance from 1.20.2 to 1.21.0

Author: bensheldon

Gemfile.lock

@@ -83,9 +83,9 @@ GEM
       unicode-display_width (>= 2.4.0, < 3.0)
     rubocop-ast (1.31.2)
       parser (>= 3.3.0.4)
-    rubocop-performance (1.20.2)
+    rubocop-performance (1.21.0)
       rubocop (>= 1.48.1, < 2.0)
-      rubocop-ast (>= 1.30.0, < 2.0)
+      rubocop-ast (>= 1.31.1, < 2.0)
     rubocop-rails (2.24.1)
       activesupport (>= 4.2.0)
       rack (>= 1.1)