Fix mocha ~1.1 incompatibility with minitest

[ahasunos]

Description

The omnibus build is currently failing because Mocha ~1.1 is incompatible with minitest v5.19 and later and it results to an error as:

.rbenv/versions/3.1.3/lib/ruby/gems/3.1.0/gems/mocha-1.16.1/lib/mocha/integration/mini_test/adapter.rb:26:in `included': uninitialized constant MiniTest (NameError)

          Mocha::ExpectationErrorFactory.exception_class = ::MiniTest::Assertion
                                                           ^^^^^^^^^^
Did you mean?  Minitest

Build link here: https://buildkite.com/chef-oss/inspec-train-main-verify/builds/876

This would require upgrade to mocha and rename the occurence of MiniTest::Mock.new to Minitest::Mock.new in our codebase.

This PR fixes the incompatibility of mocha with minitest

Related Issue

Mocha ~1.1 is incompatible with minitest v5.19 and later

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New content (non-breaking change)
• Breaking change (a content change which would break existing functionality or processes)

Checklist:

• I have read the CONTRIBUTING document.