Fix weird resized width and height if the difference of image ratio is large

[Pandede]

Intuition

Before forward the image to model, resize the image to ensure the width and height are the multiply of stride (default: 16) is mandatory. However, there is a weird behaviour when the ratio between width and height is large.

Observation

Assume that an image in shape (40, 248, 3) is ready to be resized, the method Predictor._resize_to_fixed_ratio is invoked and returns a resized image in shape (608, 3776), which is extremely large and improper. That may decrease the inference time without any rising performance.
This behaviour is also spotted in the original code.

Solution

The solution is modify the way to compute factor: it should be bound_dim / max(h,w).
After the fix, the image is resized in shape (112, 608), which is more proper.