PDK update after the Litmus Gem removal

Author: MartyEwings

Gemfile

@@ -25,7 +25,6 @@ group :development do
   gem "puppet-module-win-default-r#{minor_version}", '~> 1.0',   require: false, platforms: [:mswin, :mingw, :x64_mingw]
   gem "puppet-module-win-dev-r#{minor_version}", '~> 1.0',       require: false, platforms: [:mswin, :mingw, :x64_mingw]
   gem "github_changelog_generator",                              require: false
-  gem "puppet_litmus",                                           require: false, git: 'https://github.com/puppetlabs/puppet_litmus', ref: 'main' if Gem::Version.new(RUBY_VERSION.dup) >= Gem::Version.new('2.5.0')
 end
 group :system_tests do
   gem "puppet-module-posix-system-r#{minor_version}", '~> 1.0', require: false, platforms: [:ruby]