Update mocha requirement from ~> 1.7.0 to ~> 2.2.0

Updates the requirements on [mocha](https://github.com/freerange/mocha) to permit the latest version.
- [Changelog](https://github.com/freerange/mocha/blob/main/RELEASE.md)
- [Commits](freerange/mocha@v1.7.0...v2.2.0)

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

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

coverband.gemspec

@@ -41,7 +41,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "minitest", "= 5.18.1"
   spec.add_development_dependency "minitest-fork_executor"
   spec.add_development_dependency "minitest-stub-const"
-  spec.add_development_dependency "mocha", "~> 1.7.0"
+  spec.add_development_dependency "mocha", "~> 2.2.0"
   spec.add_development_dependency "rack"
   spec.add_development_dependency "rack-test"
   spec.add_development_dependency "rake"