Update webmock requirement from ~> 1.24.6 to ~> 3.16.2 (#532)

Updates the requirements on [webmock](https://github.com/bblimke/webmock) to permit the latest version.
- [Changelog](https://github.com/bblimke/webmock/blob/master/CHANGELOG.md)
- [Commits](bblimke/webmock@v1.24.6...v3.16.2)

---
updated-dependencies:
- dependency-name: webmock
  dependency-type: direct:development
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

fog-openstack.gemspec

@@ -34,5 +34,5 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency 'rubocop'
   spec.add_development_dependency 'shindo',  '~> 0.3'
   spec.add_development_dependency 'vcr'
-  spec.add_development_dependency 'webmock',  '~> 1.24.6'
+  spec.add_development_dependency 'webmock',  '~> 3.16.2'
 end