Skip tests properly (#31308)

* Skip tests properly

* [test_all]

* Add 'reason' as kwarg for skipTest

* [test_all] Fix up

* [test_all]

tests/models/rag/test_modeling_rag.py

@@ -91,7 +91,7 @@ def require_retrieval(test_case):
 
     """
     if not (is_torch_available() and is_datasets_available() and is_faiss_available()):
-        test_case = unittest.skip("test requires PyTorch, datasets and faiss")(test_case)
+        test_case = unittest.skip(reason="test requires PyTorch, datasets and faiss")(test_case)
     return test_case