Update webmock requirement from ~> 3.18.1 to ~> 3.19.0 (#4097)

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@v3.18.1...v3.19.0)

---
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.gemspec

@@ -100,7 +100,7 @@ Gem::Specification.new do |s|
   s.add_development_dependency("rspec-core")
   s.add_development_dependency("rspec-expectations")
   s.add_development_dependency("vcr")
-  s.add_development_dependency("webmock","~>3.18.1")
+  s.add_development_dependency("webmock","~>3.19.0")
 
   s.files = `git ls-files`.split("\n")
   s.test_files = `git ls-files -- {spec,tests}/*`.split("\n")