fix test sevennet (#393)

Author: YutackPark

tests/models/test_sevennet.py

@@ -34,8 +34,7 @@ def pretrained_sevenn_model():
     """Load a pretrained SevenNet model for testing."""
     cp = sevenn.util.load_checkpoint(model_name)
 
-    backend = "e3nn"
-    model_loaded = cp.build_model(backend)
+    model_loaded = cp.build_model()
     model_loaded.set_is_batch_data(True)
 
     return model_loaded.to(DEVICE)