Use mocha >= 2.0.1 (#39070).

git-svn-id: https://svn.redmine.org/redmine/branches/5.0-stable@22307 e93f8b46-1217-0410-a6f0-8f06a7374b81

Gemfile

@@ -99,7 +99,7 @@ end
 
 group :test do
   gem "rails-dom-testing"
-  gem 'mocha', (Gem.ruby_version < Gem::Version.new('2.7.0') ? ['>= 1.4.0', '< 2.0.0'] : '>= 1.4.0')
+  gem 'mocha', '>= 2.0.1'
   gem 'simplecov', '~> 0.21.2', :require => false
   gem "ffi", platforms: [:mingw, :x64_mingw, :mswin]
   # For running system tests