Update rubocop requirement from ~> 1.28, < 1.85 to ~> 1.28, < 1.87

Updates the requirements on [rubocop](https://github.com/rubocop/rubocop) to permit the latest version.
- [Release notes](https://github.com/rubocop/rubocop/releases)
- [Changelog](https://github.com/rubocop/rubocop/blob/master/CHANGELOG.md)
- [Commits](rubocop/rubocop@v1.28.0...v1.86.1)

---
updated-dependencies:
- dependency-name: rubocop
  dependency-version: 1.86.1
  dependency-type: direct:development
...

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

Author: dependabot[bot]

openfact.gemspec

@@ -38,7 +38,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency 'ffi', '>= 1.15.5', '< 1.18.0', '!= 1.16.0', '!= 1.16.1', '!= 1.16.2'
   spec.add_development_dependency 'rake', '~> 13.0', '>= 13.0.6'
   spec.add_development_dependency 'rspec', '~> 3.0'
-  spec.add_development_dependency 'rubocop', '~> 1.28', '< 1.85'
+  spec.add_development_dependency 'rubocop', '~> 1.28', '< 1.87'
   spec.add_development_dependency 'rubocop-performance', '~> 1.5'
   spec.add_development_dependency 'rubocop-rake', '< 1'
   spec.add_development_dependency 'rubocop-rspec', '>= 2.10', '< 4'