CI: Add new Ruby versions, use actions/checkout@v4

Author: MSP-Greg

.github/workflows/ci.yml

@@ -12,15 +12,17 @@ jobs:
       fail-fast: false
       matrix:
         os: [ ubuntu, macos, windows ]
-        ruby: [ 2.7, 3.0, 3.1, 3.2, head ]
+        ruby: [ 2.7, '3.0', 3.1, 3.2, 3.3, 3.4, head ]
         include:
           - { os: windows , ruby: mingw }
+          - { os: windows , ruby: ucrt  }
+          - { os: windows , ruby: mswin }
         exclude:
           - { os: windows , ruby: head }
 
     steps:
       - name: repo checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: load ruby
         uses: ruby/setup-ruby@v1