Add Ruby 3.4 to GitHub Actions test matrix

Author: shinokaro

.github/workflows/test-on-push.yml

@@ -9,7 +9,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ windows-latest ]
-        ruby: [ '3.0', '3.1', '3.2', '3.3' ]
+        ruby: [ '3.0', '3.1', '3.2', '3.3', '3.4' ]
     runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v4