ci: try to fix default config path

Author: karfau

.github/workflows/renovate-config-validator.yml

@@ -19,7 +19,7 @@ jobs:
       - uses: actions/checkout@v5
         with:
           repository: bettermarks/renovate-config
-          path: renovate-config
+          path: ${{ github.workspace }}/renovate-config
       - uses: ./validator
         with:
           config: ${{ inputs.config || 'renovate-config/renovate.json' }}