Update mocha requirement from ~> 1.11 to ~> 2.0 (resque#1843)

Updates the requirements on [mocha](https://github.com/freerange/mocha) to permit the latest version.
- [Release notes](https://github.com/freerange/mocha/releases)
- [Changelog](https://github.com/freerange/mocha/blob/main/RELEASE.md)
- [Commits](freerange/mocha@v1.11.0...v2.0.1)

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

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

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

Author: dependabot[bot]

Gemfile

@@ -10,7 +10,7 @@ end
 
 gem "json"
 gem "minitest", "~> 5.11"
-gem "mocha", "~> 1.11", require: false
+gem "mocha", "~> 2.0", require: false
 gem "rack-test", "~> 2.0"
 gem "rake"
 gem "rubocop", "~> 0.80"