Update rubocop-rspec requirement from ~> 3.4.0 to ~> 3.6.0

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@v3.4.0...v3.6.0)

---
updated-dependencies:
- dependency-name: rubocop-rspec
  dependency-version: 3.6.0
  dependency-type: direct:development
...

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

Author: dependabot[bot]

meta-tags.gemspec

@@ -35,7 +35,7 @@ Gem::Specification.new do |spec|
   # Code style
   spec.add_development_dependency "rubocop-rails", "~> 2.28.0"
   spec.add_development_dependency "rubocop-rake", "~> 0.6.0"
-  spec.add_development_dependency "rubocop-rspec", "~> 3.4.0"
+  spec.add_development_dependency "rubocop-rspec", "~> 3.7.0"
   spec.add_development_dependency "standard", "~> 1.31"
   # Format RSpec output for CircleCI
   spec.add_development_dependency "rspec_junit_formatter", "~> 0.6.0"