Bump rubocop-performance from 1.20.2 to 1.21.0

Bumps [rubocop-performance](https://github.com/rubocop/rubocop-performance) from 1.20.2 to 1.21.0.
- [Release notes](https://github.com/rubocop/rubocop-performance/releases)
- [Changelog](https://github.com/rubocop/rubocop-performance/blob/master/CHANGELOG.md)
- [Commits](rubocop/rubocop-performance@v1.20.2...v1.21.0)

---
updated-dependencies:
- dependency-name: rubocop-performance
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

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)