Remove github_changelog_generator puppet_metadata

.sync.yml

@@ -17,17 +17,10 @@ Gemfile:
   unmanaged: false
   optional:
     ':development':
-      - gem: 'github_changelog_generator'
-        version: '~> 1.15'
-        condition: "Gem::Version.new(RUBY_VERSION.dup) >= Gem::Version.new('2.3.0')"
       - gem: 'webmock'
         #linter_options:
         #  - 'no-parameter_types-check'
         #  - 'no-legacy_facts'
-    ':test':
-      # provides metadata2gha, needed for unit tests
-      - gem: 'puppet_metadata'
-        version: '~> 1.9.0'
 
 spec/spec_helper.rb:
   coverage_report: true