add egno (#602)

Co-authored-by: GiovanniCanali <giovanni.canali98@yahoo.it>

pina/model/block/message_passing/__init__.py

@@ -5,9 +5,13 @@ __all__ = [
     "DeepTensorNetworkBlock",
     "EnEquivariantNetworkBlock",
     "RadialFieldNetworkBlock",
+    "EquivariantGraphNeuralOperatorBlock",
 ]
 
 from .interaction_network_block import InteractionNetworkBlock
 from .deep_tensor_network_block import DeepTensorNetworkBlock
 from .en_equivariant_network_block import EnEquivariantNetworkBlock
 from .radial_field_network_block import RadialFieldNetworkBlock
+from .equivariant_graph_neural_operator_block import (
+    EquivariantGraphNeuralOperatorBlock,
+)