Updates for Ruby 3

* Various fixes for Ruby 3 compatibility
* Update rubocop configuration
* Clean up Gemfile for rubocop
* Update gem dependencies
* Use Ruby 2.7 for GHA and add Puppet 8 to test matrix

Closes simp#192

.github/workflows/pr_tests.yml

@@ -5,10 +5,11 @@
 # ------------------------------------------------------------------------------
 # Release       Puppet   Ruby    EOL
 # PE 2021.Y     7.x      2.7     Quarterly updates
+# PE 2023.Y     8.x      3.2     Quarterly updates
 #
-# https://puppet.com/docs/pe/2018.1/component_versions_in_recent_pe_releases.html
-# https://puppet.com/misc/puppet-enterprise-lifecycle
-# https://puppet.com/docs/pe/2018.1/overview/getting_support_for_pe.html
+# https://www.puppet.com/docs/pe/latest/component_versions_in_recent_pe_releases.html
+# https://www.puppet.com/products/puppet-enterprise/support-lifecycle
+# https://www.puppet.com/docs/pe/latest/getting_support_for_pe
 # ==============================================================================
 #
 # https://docs.github.com/en/actions/reference/events-that-trigger-workflows
@@ -35,7 +36,7 @@ jobs:
       - name: "Install Ruby ${{matrix.puppet.ruby_version}}"
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: 2.5
+          ruby-version: 2.7
           bundler-cache: true
       - run: |
           bundle show
@@ -49,7 +50,7 @@ jobs:
       - name: 'Install Ruby ${{matrix.puppet.ruby_version}}'
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: 2.5
+          ruby-version: 2.7
           bundler-cache: true
       - name: 'Ensure executables are installed'
         run: |
@@ -75,6 +76,9 @@ jobs:
           - label: 'Puppet 7.x'
             puppet_version: '~> 7.0'
             ruby_version: '2.7'
+          - label: 'Puppet 8.x'
+            puppet_version: '~> 8.0'
+            ruby_version: '3.2'
     env:
       PUPPET_VERSION: '${{matrix.puppet.puppet_version}}'
     steps: