Prepare for PDK update

Sync from the puppetlabs-apt module for settings related to GitHub
actions support and other CI "deprecation".

.sync.yml

@@ -1,14 +1,28 @@
+---
+".gitlab-ci.yml":
+  delete: true
+appveyor.yml:
+  delete: true
 Gemfile:
   required:
     ':system_tests':
-      - gem: 'puppet-module-posix-system-r#{minor_version}'
-        platforms: ruby
-      - gem: 'puppet-module-win-system-r#{minor_version}'
-        platforms:
-          - mswin
-          - mingw
-          - x64_mingw
       - gem: 'nokogiri'
         platforms: ruby
       - gem: 'serverspec'
         platforms: ruby
+spec/spec_helper.rb:
+  mock_with: ":rspec"
+  coverage_report: true
+.github/workflows/pr_test.yml:
+  unmanaged: false
+.github/workflows/nightly.yml:
+  unmanaged: false
+.github/workflows/spec.yml:
+  checks: 'syntax lint metadata_lint check:symlinks check:git_ignore check:dot_underscore check:test_file rubocop'
+  unmanaged: false
+.github/workflows/release.yml:
+  unmanaged: false
+.github/workflows/auto_release.yml:
+  unmanaged: false
+.travis.yml:
+  delete: true