Update __init__.py to include time features

ocf_datapipes/transform/numpy_batch/__init__.py

@@ -3,3 +3,4 @@
 from .add_fourier_space_time import AddFourierSpaceTimeIterDataPipe as AddFourierSpaceTime
 from .add_topographic_data import AddTopographicDataIterDataPipe as AddTopographicData
 from .sun_position import AddSunPositionIterDataPipe as AddSunPosition
+from .datetime_features import AddTrigonometricDateTimeIterDataPipe as AddTrigonometricDateTime