Combine validation and duplication tests for efficiency

.github/workflows/validation.yml

@@ -16,7 +16,7 @@ jobs:
       - name: Setup Python
         uses: actions/setup-python@v1
         with:
-          python-version: 3.6
+          python-version: 3.8
       - name: Install dependencies
         run: pip install -r requirements.txt
       - name: Lint YAML files