Update mocha requirement from ~> 1.0 to ~> 3.1

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@v1.0.0...v3.1.0)

---
updated-dependencies:
- dependency-name: mocha
  dependency-version: 3.1.0
  dependency-type: direct:development
...

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

Author: dependabot[bot]

Gemfile

@@ -48,7 +48,7 @@ group :test do
   gem 'syslog'
   gem 'puppet-pson', '~> 1.1'
 
-  gem 'mocha', '~> 1.0'
+  gem 'mocha', '~> 3.1'
 end
 
 group :development do