Update benchmark requirement from >= 0.3, < 0.5 to >= 0.3, < 0.6

Updates the requirements on [benchmark](https://github.com/ruby/benchmark) to permit the latest version.
- [Release notes](https://github.com/ruby/benchmark/releases)
- [Commits](ruby/benchmark@v0.3.0...v0.5.0)

---
updated-dependencies:
- dependency-name: benchmark
  dependency-version: 0.5.0
  dependency-type: direct:production
...

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

Author: dependabot[bot]

openvox.gemspec

@@ -30,7 +30,7 @@ Gem::Specification.new do |spec|
   spec.summary = "OpenVox, a community implementation of Puppet -- an automated configuration management tool"
   spec.specification_version = 4
   spec.add_runtime_dependency('base64', '>= 0.1', '< 0.4')
-  spec.add_runtime_dependency('benchmark', '>= 0.3', '< 0.5')
+  spec.add_runtime_dependency('benchmark', '>= 0.3', '< 0.6')
   spec.add_runtime_dependency('concurrent-ruby', '~> 1.0')
   spec.add_runtime_dependency('deep_merge', '~> 1.0')
   spec.add_runtime_dependency('fast_gettext', '>= 2.1', '< 5')