Set src/ as working-dir in prepare_tests action

Author: GuillemBarroso

.github/workflows/tests.yml

@@ -123,6 +123,7 @@ jobs:
         uses: pyansys/pydpf-actions/[email protected]
         with:
           DEBUG: true
+          working-directory: src
 
       - name: "List installed packages"
         shell: bash