Update rubocop-rspec requirement from ~> 2.0 to ~> 3.0

Updates the requirements on [rubocop-rspec](https://github.com/rubocop/rubocop-rspec) to permit the latest version.
- [Release notes](https://github.com/rubocop/rubocop-rspec/releases)
- [Changelog](https://github.com/rubocop/rubocop-rspec/blob/master/CHANGELOG.md)
- [Commits](rubocop/rubocop-rspec@v2.0.0...v3.0.1)

---
updated-dependencies:
- dependency-name: rubocop-rspec
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <support@github.com>

statics.gemspec

@@ -33,7 +33,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "rake", "~> 13.0"
   spec.add_development_dependency "rspec", "~> 3.0"
   spec.add_development_dependency "rspec_junit_formatter", "~> 0.4"
-  spec.add_development_dependency "rubocop-rspec", "~> 2.0"
+  spec.add_development_dependency "rubocop-rspec", "~> 3.0"
   spec.add_development_dependency "standard", "~> 1.1"
   spec.add_development_dependency "simplecov", "~> 0.1"
 end