test fix for keras.backend import error with Python 3.8

qurator/eynollah/eynollah.py

@@ -29,7 +29,7 @@ warnings.filterwarnings("ignore")
 from scipy.signal import find_peaks
 import matplotlib.pyplot as plt
 from scipy.ndimage import gaussian_filter1d
-from keras.backend import set_session
+from tensorflow.python.keras.backend import set_session
 from tensorflow.keras import layers
 
 from .utils.contour import (