add a job in test.yml workflow to test compiler flags inputs

.github/workflows/test.yml

@@ -39,6 +39,23 @@ jobs:
       - name: Check if the default build directory does not exist
         run: test ! -d build
 
+  additional-flags-usage:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out this repository
+        uses: actions/checkout@v3.3.0
+
+      - name: Use this action with additional compiler flags
+        uses: ./
+        with:
+          source-dir: test
+          targets: test_c test_cpp
+          c-flags: -Wno-unused-variable
+          cxx-flags: -Wno-unused-variable
+
+      - name: Run the build results
+        run: build/test_c && build/test_cpp
+
   specified-compiler-usage:
     runs-on: ${{ matrix.os }}-latest
     strategy: