chore: import upstream snapshot with attribution

tests/pyfunc/sample_code/streamable_model_code.py

@@ -0,0 +1,17 @@
+from mlflow.models import set_model
+from mlflow.pyfunc import PythonModel
+
+
+class StreamableModel(PythonModel):
+    def __init__(self):
+        pass
+
+    def predict(self, context, model_input, params=None):
+        pass
+
+    def predict_stream(self, context, model_input, params=None):
+        yield "test1"
+        yield "test2"
+
+
+set_model(StreamableModel())