Update webmock requirement from ~> 3.7.6 to ~> 3.14.0

Updates the requirements on [webmock](https://github.com/bblimke/webmock) to permit the latest version.
- [Release notes](https://github.com/bblimke/webmock/releases)
- [Changelog](https://github.com/bblimke/webmock/blob/master/CHANGELOG.md)
- [Commits](bblimke/webmock@v3.7.6...v3.14.0)

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

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

breathe.gemspec

@@ -31,7 +31,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "standard", "~> 0.1.5"
   spec.add_development_dependency "dotenv", "~> 2.7.5"
   spec.add_development_dependency "pry", "~> 0.12.2"
-  spec.add_development_dependency "webmock", "~> 3.7.6"
+  spec.add_development_dependency "webmock", "~> 3.14.0"
 
   spec.add_dependency "sawyer", "~> 0.8.2"
 end