Adds Ruby 3.4 to test matrix

Author: philnash

.github/workflows/tests.yml

@@ -8,7 +8,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: [2.5, 2.6, 2.7, "3.0", 3.1, 3.2, 3.3, head]
+        ruby: [2.5, 2.6, 2.7, "3.0", 3.1, 3.2, 3.3, 3.4, head]
     continue-on-error: ${{ endsWith(matrix.ruby, 'head') }}
     steps:
       - uses: actions/checkout@v2