.github/workflows/main.yml in combine_pdf-1.0.26 vs .github/workflows/main.yml in combine_pdf-1.0.27

@@ -7,11 +7,15 @@
     name: Tests
     runs-on: ubuntu-latest
     strategy:
       fail-fast: false
       matrix:
-        ruby: ["2.7", "3.0", "3.1", "3.2"]
+        ruby: ["2.7", "3.0", "3.1", "3.2", "3.3"]
+        rubyopt: [""]
+        include:
+          - ruby: "3.3"
+            rubyopt: "--enable-frozen-string-literal --debug-frozen-string-literal"
 
     steps:
       - name: Checkout code
         uses: actions/checkout@v3
 
@@ -23,6 +27,6 @@
 
       - name: Generate lockfile
         run: bundle lock
 
       - name: Run tests
-        run: bundle exec rake test
+        run: bundle exec rake test RUBYOPT="${{ matrix.rubyopt }}"