Add Ruby 3.4 to CI matrix (#47)

Author: mattbrictson

.github/workflows/ci.yml

@@ -20,7 +20,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        ruby: ["3.1", "3.2", "3.3", "head"]
+        ruby: ["3.1", "3.2", "3.3", "3.4", "head"]
     steps:
       - uses: actions/checkout@v4
       - uses: ruby/setup-ruby@v1