exclude DummyData class from testing

src/data_handling/iterator.py

@@ -130,7 +130,7 @@ class KerasIterator(keras.utils.Sequence):
             np.random.shuffle(self.indexes)
 
 
-class DummyData:
+class DummyData:  # pragma: no cover
 
     def __init__(self, number_of_samples=np.random.randint(100, 150)):
         self.number_of_samples = number_of_samples