Bump rubocop-performance from 1.19.1 to 1.21.1

Bumps [rubocop-performance](https://github.com/rubocop/rubocop-performance) from 1.19.1 to 1.21.1.
- [Release notes](https://github.com/rubocop/rubocop-performance/releases)
- [Changelog](https://github.com/rubocop/rubocop-performance/blob/master/CHANGELOG.md)
- [Commits](rubocop/rubocop-performance@v1.19.1...v1.21.1)

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

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

Gemfile.lock

@@ -203,8 +203,8 @@ GEM
  mini_portile2 (~> 2.8.2)
  racc (~> 1.4)
  ostruct (0.6.0)
- parallel (1.24.0)
- parser (3.3.1.0)
+ parallel (1.25.1)
+ parser (3.3.3.0)
  ast (~> 2.4.1)
  racc
  pg (1.5.6)
@@ -262,8 +262,8 @@ GEM
  regexp_parser (2.9.2)
  reline (0.5.2)
  io-console (~> 0.5)
- rexml (3.2.8)
- strscan (>= 3.0.9)
+ rexml (3.3.0)
+ strscan
  rspec-core (3.13.0)
  rspec-support (~> 3.13.0)
  rspec-expectations (3.13.0)
@@ -296,9 +296,9 @@ GEM
  unicode-display_width (>= 2.4.0, < 3.0)
  rubocop-ast (1.31.3)
  parser (>= 3.3.1.0)
- rubocop-performance (1.19.1)
- rubocop (>= 1.7.0, < 2.0)
- rubocop-ast (>= 0.4.0)
+ rubocop-performance (1.21.1)
+ rubocop (>= 1.48.1, < 2.0)
+ rubocop-ast (>= 1.31.1, < 2.0)
  rubocop-rails (2.15.2)
  activesupport (>= 4.2.0)
  rack (>= 1.1)