Add Ruby 3.3 to CI matrix

Author: m-nakamura145

.github/workflows/ci.yml

@@ -20,7 +20,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: ["2.7", "3.0", "3.1", "3.2", "head"]
+        ruby: ["2.7", "3.0", "3.1", "3.2", "3.3", "head"]
     steps:
       - uses: actions/checkout@v3
       - run: rm Gemfile.lock