Add Ruby 3.3 to CI matrix

Author: m-nakamura145

.github/workflows/ci.yml

@@ -30,7 +30,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: ["2.7", "3.0", "3.1", "3.2", "ruby-head", "truffleruby-head", "jruby-9.4", "jruby-head"]
+        ruby: ["2.7", "3.0", "3.1", "3.2", '3.3', "ruby-head", "truffleruby-head", "jruby-9.4", "jruby-head"]
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3