Update PDK Template

Author: MartyEwings

.sync.yml

@@ -22,7 +22,14 @@ appveyor.yml:
   unmanaged: true
 .travis.yml:
   delete: true
-
+Gemfile:
+  optional:
+    ":development":
+    - gem: github_changelog_generator
+    - gem: puppet_litmus
+      git: https://github.com/puppetlabs/puppet_litmus
+      ref: main
+      condition: Gem::Version.new(RUBY_VERSION.dup) >= Gem::Version.new('2.5.0')
 Rakefile:
   changelog_user: "puppetlabs"
 

Gemfile

@@ -24,6 +24,8 @@ group :development do
   gem "puppet-module-posix-dev-r#{minor_version}", '~> 1.0',     require: false, platforms: [:ruby]
   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]