(CONT-954) Pin changelog generator to 1.15.2

Prior to this commit, the release prep workflow intorduced was failing due to an incorrect version of the changelog generator. This commit pins it in the sync.yml and a pdk update was run. webmock is also added to .sync.yml

Author: GSPatton

.sync.yml

@@ -10,7 +10,11 @@
 appveyor.yml:
   delete: true
 Gemfile:
-  unmanaged: true
+  optional:
+    ":development":
+    - gem: github_changelog_generator
+      version: '= 1.15.2'
+    - gem: webmock
 Rakefile:
   changelog_project: provision
 spec/spec_helper.rb:

Gemfile

@@ -19,7 +19,6 @@ group :development do
   gem "json", '= 2.5.1',                         require: false if Gem::Requirement.create(['>= 3.0.0', '< 3.0.5']).satisfied_by?(Gem::Version.new(RUBY_VERSION.dup))
   gem "json", '= 2.6.1',                         require: false if Gem::Requirement.create(['>= 3.1.0', '< 3.1.3']).satisfied_by?(Gem::Version.new(RUBY_VERSION.dup))
   gem "json", '= 2.6.3',                         require: false if Gem::Requirement.create(['>= 3.2.0', '< 4.0.0']).satisfied_by?(Gem::Version.new(RUBY_VERSION.dup))
-  gem 'github_changelog_generator',              require: false if Gem::Version.new(RUBY_VERSION.dup) >= Gem::Version.new('2.5.0')
   gem "voxpupuli-puppet-lint-plugins", '~> 5.0', require: false
   gem "facterdb", '~> 1.18',                     require: false
   gem "metadata-json-lint", '~> 3.0',            require: false
@@ -35,7 +34,8 @@ group :development do
   gem "rubocop-performance", '= 1.16.0',         require: false
   gem "rubocop-rspec", '= 2.19.0',               require: false
   gem "rb-readline", '= 0.5.5',                  require: false, platforms: [:mswin, :mingw, :x64_mingw]
-  gem 'webmock'
+  gem "github_changelog_generator", '= 1.15.2',  require: false
+  gem "webmock",                                 require: false
 end
 group :system_tests do
   gem "puppet_litmus", '~> 1.0', require: false, platforms: [:ruby, :x64_mingw]

Rakefile

@@ -42,6 +42,7 @@ end
 
 PuppetLint.configuration.send('disable_relative')
 
+
 if Bundler.rubygems.find_name('github_changelog_generator').any?
   GitHubChangelogGenerator::RakeTask.new :changelog do |config|
     raise "Set CHANGELOG_GITHUB_TOKEN environment variable eg 'export CHANGELOG_GITHUB_TOKEN=valid_token_here'" if Rake.application.top_level_tasks.include? "changelog" and ENV['CHANGELOG_GITHUB_TOKEN'].nil?