a small bug on test_on_single_image.py

[oujin]

In the 36th line of test_on_single_image.py, '''img_tensor = img_tensor / 255.0''', but in the 34th line '''resize_image_with_pad''' had done it (in the 10th line of utils.preprocess.py), that means max(img_tensor)=0.0039 not 1.

[calmiLovesAI]

Fixed. Thanks!