Update rubocop-performance requirement from ~> 1.19.0 to >= 1.19, < 1.21

Updates the requirements on [rubocop-performance](https://github.com/rubocop/rubocop-performance) to permit the latest version.
- [Release notes](https://github.com/rubocop/rubocop-performance/releases)
- [Changelog](https://github.com/rubocop/rubocop-performance/blob/master/CHANGELOG.md)
- [Commits](rubocop/rubocop-performance@v1.19.0...v1.20.0)

---
updated-dependencies:
- dependency-name: rubocop-performance
  dependency-type: direct:production
...

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

voxpupuli-rubocop.gemspec

@@ -16,7 +16,7 @@ Gem::Specification.new do |s|
   s.add_runtime_dependency 'rake', '~> 13.0', '>= 13.0.6'
   s.add_runtime_dependency 'rubocop', '~> 1.59.0'
   s.add_runtime_dependency 'rubocop-minitest', '~> 0.33.0'
-  s.add_runtime_dependency 'rubocop-performance', '~> 1.19.0'
+  s.add_runtime_dependency 'rubocop-performance', '>= 1.19', '< 1.21'
   s.add_runtime_dependency 'rubocop-rake', '~> 0.6.0'
   s.add_runtime_dependency 'rubocop-rspec', '~> 2.25.0'
 end