Update models.py

[Rookiecoder-Wang]

A Very Easy Bug Fix(A Rookie's First Test)
For This Error RuntimeError: Error(s) in loading state_dict for Yolov4:

[Rookiecoder-Wang]

If without this fix,an error will occured when we running demo_pytorch2onnx.py,just like this
Traceback (most recent call last):
File "demo_pytorch2onnx.py", line 96, in
main(weight_file, image_path, batch_size, n_classes, IN_IMAGE_H, IN_IMAGE_W)
File "demo_pytorch2onnx.py", line 69, in main
onnx_path_demo = transform_to_onnx(weight_file, batch_size, n_classes, IN_IMAGE_H, IN_IMAGE_W)
File "demo_pytorch2onnx.py", line 20, in transform_to_onnx
model.load_state_dict(pretrained_dict)
File "F:\Pythons\envs\modelt\lib\site-packages\torch\nn\modules\module.py", line 830, in load_state_dict
self.class.name, "\n\t".join(error_msgs)))
RuntimeError: Error(s) in loading state_dict for Yolov4:
Missing key(s) in state_dict: "neck.conv1.conv.0.weight", "neck.conv1.conv.1.weight", "neck.conv1.conv.1.bias", "neck.conv1.conv.1.running_mean", "neck.conv1.conv.1.running_var", "neck.conv2.conv.0.weight", "neck.conv2.conv.1.weight", "neck.conv2.conv.1.bias", "neck.conv2.conv.1.running_mean", "neck.conv2.conv.1.running_var", "neck.conv3.conv.0.weight", "neck.conv3.conv.1.weight", "neck.conv3.conv.1.bias", "neck.conv3.conv.1.running_mean", "neck.conv3.conv.1.running_var", "neck.conv4.conv.0.weight", "neck.conv4.conv.1.weight", "neck.conv4.conv.1.bias", "neck.conv4.conv.1.running_mean", "neck.conv4.conv.1.running_var", "neck.conv5.conv.0.weight", "neck.conv5.conv.1.weight", ········