Add Ruby 3.2 to the CI matrix

Author: mishina2228

.github/workflows/ci.yml

@@ -10,7 +10,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby-version: ['2.3', '2.4', '2.5', '2.6', '2.7', '3.0', '3.1', 'ruby-head']
+        ruby-version: ['2.3', '2.4', '2.5', '2.6', '2.7', '3.0', '3.1', '3.2', 'ruby-head']
     continue-on-error: ${{ matrix.ruby-version == 'ruby-head' }}
     steps:
       - uses: actions/checkout@v3