CI: add Ruby 4.0 and 3.4 to the test matrix (#36)

Author: orien

.github/workflows/test.yml

@@ -8,9 +8,9 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: [ '2.7', '3.0', '3.1', '3.2', '3.3' ]
+        ruby: [ '2.7', '3.0', '3.1', '3.2', '3.3', '3.4', '4.0' ]
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Install libexiv2-dev
         run: |
           sudo apt-get update --quiet